Drivetrain

4L80E / 4L85E overdrive swap

Still do the 4L80E, bought as a professionally built unit with a builder-matched lock-up converter. The corrections: Path B should be the Gearstar Big/Small Block Level 2 (SKU GS4L80ELT2, $5,195, core $650, stall 1600-2200), not the LS SKU. Path A is the Gearstar BBC Level 3 (GS4L80ELTL3, $6,295, stall 2600-3600,…

Research date 2026-10-12. Prices are US list/retail as found on the pages cited; "(search)" means the price came from a search-result summary and the page itself could not be fetched (many retailer and forum pages returned HTTP 403). Anything marked unconfirmed is an estimate or recollection, not a retrieved fact.

The pick

Good
about $4,400-$5,900 (junkyard core + DIY rebuild + US Shift Quick 4 + TPS kit + hardware; hard parts, converter and driveshaft are unconfirmed estimates)
Better
about $7,600-$8,500 with the Gearstar BBC Level 2 ($5,195) + Quick4 kit with TPS ($950) + hardware; about $6,100-$7,000 only if TCI confirms a suitable converter on the $3,796 StreetFighter
Best
about $8,750-$10,550 (Gearstar BBC Level 3 at $6,295 + controller + hardware; Level 4 not recommended; Bowler adds roughly $3,000+)

Do the 4L80E, buy it built, and buy it from someone who will tune the converter to the cam. For a truck meant to be bulletproof in a teenager's hands in 2042, a professionally built unit with a warranty beats a home rebuild of a 25-year-old junkyard core, even though DIY is feasible for this owner. A 4L80E has no TV cable or vacuum modulator, so the build is free of the vacuum-brake conflict that a TH400 modulator would add.

  • Path B (stock bottom end, ~400-450 hp): Gearstar Big/Small Block Level 2 (GS4L80ELT2, $5,195), stall range 1600-2200, which suits a moderate cam and the "drivability wins" goal. (The earlier text asked for 2,200-2,600 stall from the L2, which is above that unit's listed range; if a lopey cam wants more, step up to the Level 3 or ask Gearstar what they can do.) The TCI StreetFighter ($3,796) is only worth considering if TCI confirms a converter at or below ~2,600 stall; its StreetFighter converter is 3,000+ stall. Pair with a US Shift Quick 4.
  • Path A (forged, aluminum heads, ~500+ hp, 540 lb-ft): Gearstar BBC Level 3 ($6,295), 9-10 in. converter. A stock 4L80E is rated only 440 lb-ft input (4L85E 460) [2][17], so the 540 lb-ft engine needs the upgraded L3 internals. Gearstar's L3 lists 2,600-3,600 stall for a 9 or 10 in. billet Yank lock-up; that floor is at or above what this cam needs. Ask Gearstar in writing what flash it will build for a 489 (520-560 lb-ft), the Magnum 232 / 230-230 cam card, 3.70 gears, a 27.9 in. tire and about 4,300 lb; the target is an actual flash of 2,300-2,600 rpm, which may need a converter built below the catalog 2,600 label (not confirmed that Gearstar will do this). If they will not, buy the converter from an independent builder and have Gearstar fit it. The L2's 1,600-2,200 converter range fits the cam but its internals are rated 500 lb-ft, below the 489's torque, so it is not an option for Recipe 2. This replaces the earlier 'spec stall 2,600-3,000' line. The Level 4 3,400 stall is not recommended for a 35-minute interstate commute.
  • Controller: US Shift Quick 4 for a carbureted truck (Gearstar's $950 kit includes the TPS); the Terminator X Max Stealth 4150 only if the fuel section ends up choosing EFI, since then you buy one box for both jobs.
  • Alternative worth pricing (missing from the first draft): a Gear Vendors overdrive unit bolted behind the rebuilt TH400 keeps the TH400 and adds a 0.78-ish overdrive, with no computer. A forum post put it at roughly $2,600-$3,000 (search summary, unconfirmed; no vendor page checked), plus the TH400 rebuild and a shorter driveshaft change. It is manual-selected (or by a switch), an extra moving part, and hard to wire for a teenage driver; the 4L80E is the cleaner long-term answer, but a knowledgeable square-body builder will ask about it.
  • Gears and tires: 3.73 with a ~29-30 in. tire is the sweet spot (below) - but the project's recommended rear tire is 27.9 in spec (27.0 rolling), so with the Ford 9" the equivalent ratio is 3.70 (section 90 and 91) and a GM 12-bolt would be 3.42-3.73. Do not go to 4.10 unless the tire is 32 in.+. Tire-diameter basis (added in the integration pass, 2026-10-12): the rpm figures here use spec-sheet (unloaded) tire diameters. Published revolutions per mile imply a loaded rolling diameter about 3% smaller (Nitto NT555 G2 275/50R17: 27.87 in spec, 746 rev/mi = 27.03 in; BFGoodrich Radial T/A 275/60R15: 28.0 in spec, 743 rev/mi = 27.14 in; section 91), so real cruise rpm is about 3% higher than tabulated. Example: the recommended 4L80E + Ford 9" 3.70 + 275/50R17 is 2,175 / 2,343 rpm at 65 / 70 mph at spec diameter and about 2,240 / 2,415 measured. The recommended rear tire is 27.9 in spec (27.0 in rolling), not the 29-30 in tire some tables here assume; choose the gear after the tire.

Highway RPM (4th gear 0.75, converter locked; computed rpm = mph x ratio x 336 / tire diameter)

Axle Tire dia. 65 mph 70 mph Same truck in TH400 (1.00) at 70 mph
3.42 29 in. (255/70R15) 1,932 2,080 2,774
3.42 30 in. (275/60R17) 1,867 2,011 2,681
3.73 29 in. 2,107 2,269 3,025
3.73 30 in. 2,037 2,193 2,924
3.73 32 in. 1,909 2,056 2,742
4.10 29 in. 2,316 2,494 3,325
4.10 30 in. 2,239 2,411 3,214
4.10 32 in. 2,099 2,260 3,014

Owner reports line up: a square-body 4L80E at 3.73 saw about 1,800 rpm at 60 mph locked, and one 454/4L80 builder saw about 2,000 rpm at 65 mph [31]. A 454 loafing at 2,000-2,300 rpm is happy. First gear stays 2.48, so a 3.73 axle gives 9.25:1 overall launch ratio and a 4.10 gives 10.2:1.

If the owner prefers simplicity: a rebuilt TH400 is cheaper and needs no controller, but would turn ~2,800-3,000 rpm at 70 on the same axle. (TH400 costs are covered in the companion section.)

Why it matters

The 4L80E is the closest thing to a "modern TH400". It is built on the TH400 architecture: the first three ratios are identical (2.48 / 1.48 / 1.00), it adds a 0.75 overdrive, a lock-up converter, and it uses the same 32-spline output shaft and a Chevy-pattern bellhousing cast into the case [1][2][3]. That makes it the one overdrive automatic that is truly at home behind a big-block Chevy and a 500 lb-ft class engine. It is also the only option that fixes the owner's stated pain point: a 35-minute, 65-70 mph interstate commute without "spun to the moon" revs.

The price of admission is that it is electronic. Unlike a TH400 ("needs no controller at all" [3]), the 4L80E needs a controller for shift points, line pressure and converter lock-up, plus a throttle-position signal and a vehicle-speed signal. In a 1977 truck with a Quadrajet or Edelbrock/Holley carb that means a standalone controller (US Shift Quick 4, Compushift, TCI EZ-TCU, or Chevrolet Performance SuperMatic) plus a carb TPS kit; with throttle-body EFI (Holley Terminator X Max / Stealth 4150) the EFI computer can run the trans itself [4][5][6]. The owner is comfortable with wiring, so this is mostly a matter of choosing a clean, supportable system for a truck that must run reliably through ~2042.

It is also bigger and heavier. Sources disagree on weight: Gearstar's blog puts the TH400 at about 130 lb and the 4L80E at about 187 lb (+57 lb) [3], while dieselhub and chevyhardcore list the 4L80E at 236 lb (dieselhub: 236 dry / 260 with fluid) against roughly 135-150 lb for a TH400 (search summaries) [2][7]. Plan on +55 to +100 lb over a TH400, not the +40-55 lb first stated (verification 2026-10-12). Length is about 1.5-2 in. longer than a TH400 per square-body owners, and Gearstar quotes 26.25 in. for the 4L80E itself [1][8]. So expect a rearward crossmember move and a new custom driveshaft (the yoke sits further back; measure the installed truck).

Options

A. Transmission (built unit with converter), for a 2WD big-block Chevy

Tier Brand & model Part # Price (vendor, checked 2026-10-12) Link Notes
Good (DIY) Used 4L80E core, 1991-2003 GM 3/4-ton or 1-ton truck/Suburban/van, rebuilt at home with Raybestos Red deluxe kit Kit for 97-on listed Core about $450-$500 (forum reports); Raybestos Red HP deluxe kit $589.95 (search); Transgo shift kit $125 (search) [9][10] Cheapest, but hard parts (input/main shafts, drums) and a lock-up converter are extra. Hard-part and converter cost unconfirmed (budget $800-$1,500 more). Local shop rebuild quote seen: $1,400 with converter on a 1981 C20 (older thread, not current) [11]
Better (conditional) TCI StreetFighter 4L80E lock-up, 2WD Chevy/GMC (listed for 1991-98 V8 2WD trucks) EDL271000 $3,795.95 (cjponyparts via search summary; page returns 403, re-confirmed by a second search 2026-10-12) [12] Built unit; whether a converter is included and what stall is NOT confirmed. TCI's StreetFighter 4L80E converter (242940) is a 3,000 rpm unit that TCI says runs about 3,400-3,600 on a big block (search summary) and costs $1,599.95 separately (butlerperformance, fetched) [27]. That is too loose for this brief, so only buy this if TCI will supply a converter at or below ~2,600 stall. Super StreetFighter (875 hp) variant TCI 271050 listed at $3,875.95 (search) [12]
Better (recommended Path B) Gearstar 4L80E 2WD Big/Small Block Level 2 (500 hp / 500 lb-ft) GS4L80ELT2 (the LS version is GS4L80ELSL2; do NOT order that for a Mark IV) $5,195.00 + $650 core (BBC page) + about $200 ATF (gearstar.com, fetched 2026-10-12) [13a][13] 13 in. lock-up, 1600-2200 stall, 31 in. from mounting surface to tailshaft tip, mount center 30.5 in. Page states it is for big and small block Chevy 2WD. Search snippets earlier showed $4,595; the fetched page is the current number
Best Gearstar 4L80E 2WD Big/Small Block Level 3 (600 hp / 600 lb-ft) GS4L80ELTL3 $6,295.00 + $750 core + about $200 ATF (gearstar.com, fetched 2026-10-12) [14] 9-10 in. billet Yank lock-up, 2600-3600 stall, hardened steels, heat-treated shafts, 31 in. long, mount center 30.5 in. Right class for a 540 lb-ft path-A engine (a stock 4L80E is only rated 440 lb-ft input)
Best (max) Gearstar 4L80E 2WD Big/Small Block Level 4 (800 hp / 750 lb-ft) GS4L80ELTL4 (BBC; the earlier GS4L80ELSL4 / link was the LS version) $7,295.00 + $750 core + about $200 ATF (gearstar.com, fetched 2026-10-12) [15a] Billet 10 in. Yank lock-up, 300M shafts. Overkill, but a "never touch it again" unit. Stall 2800-3400 is too loose for a street 454 without the right cam; ask for a tighter converter. Gearstar also lists Level 5 ($8,895) and Pro Series ($10,495) for BBC; not needed [33]
Best (boutique) Bowler Tru-Street 4L80E up to 650 lb-ft not retrieved $10,526.95 (search) [16] Premium price; not needed for this power. Other builders named (Level 10, Coan, PATC, Performance Automatic) were not price-confirmed

Note: The 4L85E is the same case with 5-pinion reaction/output carriers (460 vs 440 lb-ft input rating), so a 4L85E core is a slight upgrade but not required, and builders such as Gearstar sell hard parts either way [1][17].

B. Controller and sensors

Tier Brand & model Part # Price (vendor, checked 2026-10-12) Link Notes
Good US Shift Quick 4 Gen 2 (controller, harness, instructions) SKU 2162 $795.00 (dieselconversion.com, fetched) [18] Standalone, no laptop; 4 shift tunes, lock-up and line-pressure control, data logging; carb or EFI
Good /Better US Shift Quick4 kit via Gearstar not stated $950.00 (gearstar.com, fetched 2026-10-12) [19] Includes harness, a throttle position sensor kit as standard, and a tune pre-loaded for Gearstar transmissions; state carb vs EFI when ordering. Easiest if buying a Gearstar trans. This kit makes a separate TPS purchase unnecessary for carb use (confirm which carb brand the supplied TPS bracket fits)
Better TCI EZ-TCU (4L60E/65E/70E/75E/80E/85E, handheld programmer) TCI302820 Current US price not confirmed. Search summary 2026-10-12: eBay $800-$1,162; a related FAST EZ-TCU kit $857.39 at Fidanza. The earlier "$660 at Summit" was an old forum figure and is withdrawn. Australian listing A$1,978.70, sold out [20] [20] Hand-held tuner, switchable calibrations
Better Chevrolet Performance SuperMatic controller for 4L80E, carbureted 809-19332780 (GM 19332780) About $2,249 at JEGS; $1,949-$2,334 at SDPC (search summaries 2026-10-12; JEGS page returns 403) [21] GM-branded system sold for carbureted or Ram-Jet engines, laptop-programmed. Costs about 2.5x a Quick 4; not recommended on price
Best (EFI path only) Holley Terminator X Max Stealth 4150, 4L60E/4L80E trans control 550-1011 / 1012 / 1013 (shiny / black / gold, 4-injector; see the SKU map in section 04) 550-1013 $2,499.95 on sale (regular $2,812.95; out of stock, special order) at sdparts, fetched 2026-10-12; 550-1011 $2,471.95 (search summary); earlier $2,158.95-$2,536.95 range was a search-summary spread [4][5] Four 100 lb/hr injectors, supports ~650 hp NA (corrected in the integration pass: 550-1011/-1012/-1013 are the four-injector trans-control kits; 550-1014/-1015/-1016 are the eight-injector, 1,250 hp versions, listed as discontinued on holley.com; an earlier note here mistakenly read 1015 as a four-injector finish option); trans control for pre-2009 4L60E/4L80E built in. This is a whole EFI system, not just a controller
Compushift Compushift 4L80E controller not retrieved about $900 on eBay / $1,200 direct, from an old forum thread via search summary; unconfirmed, may be stale [22] Thread returns 403; verify current price and support
Carb TPS (US Shift) US Shift TPS kit for Edelbrock carburetor (Quick4/Quick6) 820142 $199.99 (wildhorses4x4.com, fetched 2026-10-12) [36] "Most Edelbrock carburetors with electric choke"; NOT compatible with Edelbrock AFB original-equipment carbs. This resolves the earlier "no AVS2 TPS kit found" concern: an AVS2 has an electric choke so it should work, but confirm with US Shift before buying. US Shift also sells Holley/Street Demon carb kits [37]
Carb TPS (Holley) Holley TPS kit for electric-choke 4150/4160 carbs 534-202 $207.95 (MSRP $233.95); other retailers $184-$229 (search summary 2026-10-12) [6] Made for 4L60E/4L80E use with Holley electric-choke carbs

C. Swap hardware

Item Brand & model Part # Price (vendor, checked 2026-10-12) Link Notes
Crossmember Hooker BlackHeart 1973-87 C10 2WD crossmember kit, 4L80E/4L85E version BHS500 base kit (BHS549 for 4L80E/4L85E) $259.95 (psiconversion.com, fetched) [24][25] Built around the BHS540 LS engine mounts and 3 in. dual exhaust clearance. It is designed for LS swaps; with a Mark IV 454 on stock mounts the location will not match, so treat as a starting point or fabricate
Flexplate Allstar BBC flexplate, 168 tooth, external balance, 2-piece rear seal ALL26825 price not confirmed (listing found in search 2026-10-12; spec confirmed: 168T, external balance, 2-piece seal, dual 10-3/4 and 11-1/2 in. converter patterns) [26] This is the right type for a 1977 Mark IV 454. TCI 399973 is the 1991-95 Gen V ONE-piece-seal part, priced A$300.80 (Australian dollars, roughly US$195), and is wrong for this engine. Buy the flexplate to match the converter's actual bolt circle (confirm with the trans builder); one owner found only 3 of 6 holes lined up on a mismatched dual-pattern plate [26]
Converter (separate) TCI Street Fighter 4L80E lock-up billet, 3000 stall (10 in.) 242940 $1,599.95 (butlerperformance.com, fetched 2026-10-12) [27] 3,000 stall is too loose for this brief. Circle D Pro Series 245 mm, 3200-3400 stall, dual 11.06/11.5 in. 6-bolt patterns: $1,159.00 (michiganmotorsports.com, fetched 2026-10-12; listed for LS applications, also too loose) [28]. Comp Cams Super StreetFighter price not confirmed
Shifter Lokar column-shift cable kit for 4L80E not retrieved price not confirmed [29] Owners report it only fits 4L80Es with the short shifter shaft and that factory linkage on a GM column may need mods
Speedo Dakota Digital electronic-to-mechanical cable drive adapter ECD-200BT (also DAKECD-200BT-1/-2) $400.00 (psiconversion.com, fetched 2026-10-12); about $380 at Walmart and MSRP $345 per search summary. The earlier A$753-$793 figure was Australian dollars and is withdrawn [30][38] For keeping a cable-driven cluster; waterproof, 36 in. cable, thread-on or clip-on. A Dakota digital cluster fed by a VSS is the alternative; price not confirmed

Swap cost rollup (parts only; owner labor free; excludes machine work)

Tier What's in it Estimated total
Good Junkyard core ($500) + rebuild kit ($590) + hard parts/converter (unconfirmed, $800-$1,500) + US Shift Quick 4 ($795) + Edelbrock/Holley TPS kit ($200) + crossmember ($260) + flexplate (about $150-$300) + driveshaft, shifter linkage, cooler lines, speedo adapter ($400) (unconfirmed, $1,000-$1,800) about $4,400-$5,900 (recomputed 2026-10-12; was $4,500-$5,500)
Better Gearstar BBC L2 ($5,195) + Quick4 kit with TPS ($950) + hardware allowance ($1,500-$2,300). TCI StreetFighter ($3,796) is a cheaper variant only if the converter and stall are confirmed (it would add up to $1,600 if the converter is separate) about $7,600-$8,500 with Gearstar L2; about $6,100-$7,000 only if the TCI unit with a suitable converter pans out
Best Gearstar BBC L3 ($6,295) (L4 $7,295 not recommended) + Quick 4 ($950) or Terminator X Max EFI (counted in the fuel section) + hardware ($1,500-$2,300) + new electronic cluster/speedo about $8,750-$10,550 (Bowler would add roughly $3,000+)

Core charges ($750 Gearstar) are refundable on return of the old unit; they are not included above.

Fitment & gotchas

  • Length and crossmember. Square-body owners say the 4L80E is about 1.5-2 in. longer than a TH400 and the crossmember moves rearward [8]. The brief's "26 in. vs 24.5 in." is consistent with this: Gearstar lists the 4L80E at 26.25 in., and its built units at 31 in. overall with the mount center at 30.5 in. [1][13]. I did not find an independently measured TH400 figure, so measure on the truck from the bellhousing face to the mount pad. Hooker's BHS500 + BHS549 is the only bolt-in 4L80E crossmember found, and it is tied to LS motor mounts [24][25].
  • Output shaft. The 4L80E and TH400 both use a 32-spline output shaft (Gearstar guide, fetched; the TH350 is the 27-spline one) [1], so the slip-yoke spline carries over, but one builder reports shortening the 4L80E output shaft about 1/8 in. to match a TH400 [1][31] (secondhand; unconfirmed).
  • Driveshaft. A 4x4 comparison on a gmsquarebody thread shows 48.99 in. (4L80E) vs 58.75 in. (TH400) for a different, transfer-case setup, so numbers do not transfer to a 2WD truck [8]. Plan on a custom driveshaft from a shop that measures the finished install, and check pinion angle with the new crossmember location.
  • Bellhousing and flexplate. The case includes a Chevy bellhousing, so the 454 bolts straight on, but use a 168-tooth externally balanced BBC flexplate (dual 10.75/11.5 in. pattern) and check converter-to-flexplate spacing (about 1/8 in. clearance when seated) [26]. The converter size claim of "~310 mm" in the first draft could not be verified (Gearstar's L2 uses a 13 in. converter, L3/L4 a 9-10 in.); confirm the starter and dust-cover fit with the builder. Reports also say the bellhousing's left side can touch the transmission tunnel and may need relief (search summary, unconfirmed).
  • Shifter. A 7-position shifter (P, R, N, OD, D, 2, 1) is the design intent [1]. The 1977 column is a 3-speed-automatic (TH400-style) column. Square-body threads (mostly 4x4s) say that to reach every gear you need an overdrive-pattern column or detent plate, a lengthened shift rod, the TH400 shift arm on the 4L80E, and the linkage pivot moved rearward; a common compromise is losing manual-low or the Park detent, and several owners simply gave up manual first gear [29][39]. Lokar's cable kit only fits 4L80Es with the short shifter shaft (two lengths exist, depending on the electronics) [29]. Treat column shift as a fabrication project; a floor shifter is the low-risk fallback.
  • Speedometer. The 1977 cluster is cable-driven and the 4L80E has an electronic output-speed sensor, so you need an electronic-to-cable adapter (Dakota Digital) or a new cluster [30]. The tuner/controller will also want a speed signal; check that the same sensor can feed both.
  • TPS. Holley 534-202 fits electric-choke Holley carbs [6]. For an Edelbrock carb, US Shift sells a TPS kit (SKU 820142, $199.99) for "most Edelbrock carburetors with electric choke", excluding AFB original-equipment carbs [36]; the AVS2 is not named on the page I could fetch, so confirm with US Shift before buying. Gearstar's $950 Quick4 kit includes a TPS kit [19]. This replaces the earlier warning that no AVS2 TPS option existed.
  • Cooler and lines. The 4L80E has a bigger cooling demand and a lock-up clutch that adds heat. Plan a proper auxiliary cooler; cooler line fitting sizes were not verified.
  • Hot-rod weight. Adds ~55-100 lb (see the weight note at the top) at the front-center of a frame that will also see a big block; negligible for handling, but check the transmission mount and the floor tunnel for heat and clearance.
  • Wiring. The harness is the weak point (cracking of the external wiring harness is a documented issue on 4L85E units [17]). Buy a new harness with the trans, or ask the builder to supply one.

How it touches other systems

  • Cam and converter. Pick the converter stall after the cam: a street hydraulic roller with ~230 degrees at .050 and a mean idle wants an actual flash of roughly 2,300-2,600 on a 500 lb-ft engine (catalog labels run lower than the flash; section 90); a loose 3,400 converter plus 3.73 gears will make a loafing highway cruise flare between lock-up cycles. Ask the builder.
  • Vacuum power brakes. The 4L80E does not use a vacuum modulator, so the transmission does not compete with the booster for vacuum. A lopey cam can still starve the booster; see the brake and cam sections.
  • Fuel system choice. Carb: needs standalone controller + TPS. EFI (Terminator X Max): one computer runs both, with the extra cost counted in the fuel section [4][5].
  • Exhaust and crossmember. Dual 3 in. pipes plus X-pipe must clear the rearward-shifted crossmember; Hooker's kit is designed around 3 in. duals [24].
  • Axle and tire. Axle ratio and tire diameter set highway rpm; see the table above and the rear axle section. 3.73 is also easier on parts availability with a 12-bolt.
  • Cooling. Trans cooler placement interacts with the Cold Case radiator and fan shroud.
  • Electrical. The controller needs switched 12 V, a TPS reference and brake input; coordinate with the new wiring harness and the dash/gauge choice (electronic cluster would remove the speedo adapter).

Check on the truck

  1. Is the factory column shift staying, or is a floor shifter acceptable? (This decides the shifter budget.)
  2. Carb (AVS2 vs Holley) or EFI? If AVS2, confirm with US Shift that kit 820142 fits it (see TPS note).
  3. Which rear axle and ratio? 3.73 is recommended; 4.10 pushes highway rpm to 2,300-2,500.
  4. Tire diameter and wheel size (affects the rpm table above).
  5. Measure frame crossmember position and the original TH400 mount-pad to bellhousing-face distance; measure the unloaded driveshaft angle.
  6. Do you want the converter chosen by the builder (recommended) or bought separately?
  7. Is a speedometer cable adapter acceptable, or will the cluster be replaced?
  8. Confirm flexplate (two-piece rear seal, external balance) and starter on the Mark IV.

Fact-check notes

Adversarial check, 2026-10-12. Fetched about 35 URLs successfully; roughly 15 more returned HTTP 403 (retailer and forum sites block the fetcher, so they are blocked, not proven dead). No cited URL was found to be a 404.

Confirmed as written: Gearstar L3 price/SKU/stall/core ($6,295, GS4L80ELTL3, 2600-3600, $750); US Shift Quick 4 SKU 2162 $795 and the Gearstar Quick4 kit $950 (includes TPS, specify carb or EFI); Hooker BHS500 $259.95 with BHS549 for 4L80E/4L85E, 3 in. duals, built around BHS540 LS mounts; gear ratios 2.48/1.48/1.00/0.75 (dieselhub: 2.482/1.482/1.00/0.750); 32-spline output; 440 lb-ft (4L80E) / 460 (4L85E); 4L85E harness-cracking issue; the $1,400 C20 rebuild quote (2015 thread, stale); all rpm-table arithmetic (re-computed, correct; 255/70R15 is about 29.1 in. and 275/60R17 about 30.0 in.).

Changed:

  1. Gearstar SKU/link errors. GS4L80ELSL2 and GS4L80ELSL4 are the LS-engine versions; the Mark IV needs the Big/Small Block versions (L2 GS4L80ELT2, core $650; L4 GS4L80ELTL4). Added links and the correct SKUs. Prices are the same.
  2. Recommendation internal conflict. The Path B text asked for a 2,200-2,600 stall from the L2, but the L2 is listed at 1600-2200. Rewritten.
  3. TCI StreetFighter EDL271000 downgraded. Converter inclusion and stall are unconfirmed, and TCI's StreetFighter 4L80E converter is a 3,000+ stall (reported 3,400-3,600 on a big block), too loose for this brief. Price $3,795.95 re-confirmed by search only. Not recommended unless TCI confirms a tight converter. TCI converter 242940 now priced at $1,599.95 (fetched).
  4. Weight understated. Sources range from 187 lb (Gearstar) to 236 lb dry / 260 wet (dieselhub, chevyhardcore) versus 130-150 lb for the TH400; corrected to +55 to +100 lb.
  5. Flexplate price was in Australian dollars (A$300.80) and the part is for a one-piece-seal Gen V engine; added the correct Mark IV-type part (Allstar ALL26825 spec confirmed; price not confirmed) and a warning to match the converter bolt circle.
  6. Dakota Digital adapter price replaced with a US figure ($400 at PSI, fetched; the A$ numbers withdrawn).
  7. TPS: the "no AVS2 TPS kit found" caution is out of date. US Shift sells TPS kit 820142 for most Edelbrock electric-choke carbs ($199.99, fetched); AVS2 compatibility itself is not stated on the page, so confirm. Holley 534-202 price added ($207.95).
  8. SuperMatic controller priced (about $2,249 JEGS per search summary), EZ-TCU "$660" withdrawn (eBay $800-$1,162), Terminator X Max prices updated (550-1013 $2,499.95 fetched), Compushift price kept as stale/unconfirmed.
  9. Column shift gotcha strengthened: overdrive-pattern column or detent plate, shift-rod and pivot changes, common loss of manual-low or Park detent (from square-body threads, mostly 4x4s).
  10. Added the Gear Vendors overdrive-on-TH400 alternative (price unconfirmed), unverified "310 mm converter" claim removed, tier totals recomputed.

Still unconfirmed and left flagged: hard-part/converter/driveshaft costs for the Good tier, Hooker crossmember position with a stock-mount Mark IV (the kit is LS-oriented), exact crossmember rearward move (a search summary said about 6 in.; a 4x4 thread said "one bolt hole"; measure the truck), Gearstar warranty terms, whether the Terminator X Max Stealth ships with four or eight injectors, and the 4L80E yoke type on 2WD units.

Sources 41

  1. gearstar.com (fetched)
  2. dieselhub.com (fetched)
  3. gearstar.com (fetched)
  4. cjponyparts.com (search result only)
  5. billysspeedshop.com (search result only)
  6. lmperformance.com (search result only)
  7. chevyhardcore.com (search result only)
  8. gmsquarebody.com (fetched)
  9. tahoeyukonforum.com (search result only)
  10. ebay.com (search result only)
  11. gmsquarebody.com (fetched)
  12. cjponyparts.com (search result only)
  13. gearstar.com (fetched)
  14. gearstar.com (fetched)
  15. gearstar.com (fetched)
  16. bowlertransmissions.com (search result only)
  17. gearstar.com (fetched)
  18. dieselconversion.com (fetched)
  19. gearstar.com (fetched)
  20. enginemaster.com.au (fetched)
  21. jegs.com (search result only)
  22. ck5.com (search result only, page 403)
  23. jegs.com (search result only)
  24. cjponyparts.com (search result only)
  25. psiconversion.com (fetched)
  26. totalperformance.net.au (search result only)
  27. butlerperformance.com (search result only)
  28. michiganmotorsports.com (search result only)
  29. ck5.com (search result only)
  30. enginemaster.com.au (search result only)
  31. 67-72chevytrucks.com and gmsquarebody.com (search results only; 403 on fetch, claims are summaries)
  32. ck5.com (search result only)
  33. gearstar.com (search result only)
  34. ck5.com (search result only)
  35. gbodyforum.com (search result only)
  36. 13a. gearstar.com (fetched 2026-10-12; Big/Small Block Level 2, SKU GS4L80ELT2)
  37. 15a. gearstar.com (fetched 2026-10-12; Big/Small Block Level 4, SKU GS4L80ELTL4)
  38. wildhorses4x4.com (fetched 2026-10-12)
  39. streetmusclemag.com (fetched 2026-10-12)
  40. psiconversion.com (fetched 2026-10-12)
  41. gmsquarebody.com (fetched 2026-10-12; 4L80E column-shift linkage discussion)
  42. sdparts.com (fetched 2026-10-12; Holley 550-1013)
  43. gearstar.com (fetched 2026-10-12; Gearstar price list)