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LS swap transmissions: 4L60E vs 4L80E, T56, TKX & 8HP
The short answer: pick by power, by what will run the transmission, and by what fits your tunnel.
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- 4L60E: the cheap, compact electronic automatic for a mild street LS (stock about 300–360 lb-ft). It needs a computer that shifts it.
- 4L80E: for big power, boost or towing (GM rates it 440 lb-ft). It is heavier and longer, takes a 4L80E-pattern flexplate and often crossmember or tunnel work.
- TH350 / TH400 / Powerglide: no computer needed, but the flexplate and converter setup changes (Step 3).
- Manual: the Tremec TKX (600 lb-ft) is the slim 5-speed for tighter tunnels; the 6-speed Tremec Magnum is rated 700 lb-ft. A used factory T56 is rated far lower depending on the car it came from (see the tag table), and a T56-size case may need firewall or tunnel work.
- 6L80, 8L90 or ZF 8HP: modern gearing, but choose the controller (and for the 8HP the adapter) before you buy the transmission.
Below: how to choose step by step, every transmission compared, T56 tags, controllers and the flexplate and driveshaft details. Already know your vehicle and engine? The swap planner builds the parts list with your transmission in it.
How we put this guide together
Transmissions were the single biggest topic in our research: 467 of the 2,012 LS swap questions we pulled from forum threads involved the transmission, the flexplate or converter, the clutch, the crossmember or the driveshaft behind it. The recurring ones: do I need a spacer for a 700R4?, which flexplate goes with a 4L80E on a 5.3?, what runs an electronic transmission? and how long does the driveshaft need to be? The answers below use GM and Tremec ratings and the controller makers' own specs.
Step 1: Pick the transmission for what you're building
Start with how the transmission is controlled, because that decides what else you have to buy.
- GM electronic automatics (4L60E, 4L80E, 6L80/6L90): they need a computer that runs them. That's either the factory PCM they came with, or a Holley Terminator X Max, which has 4L60E/4L80E control built in and runs a 6L80/6L90 with Holley's 558-499 kit (2WD only; needs Holley V3 software, build 100 or later). See the ECU comparison.
- Older GM automatics (TH350, 700R4, Powerglide, TH400): no computer, but they need a different flexplate setup (Step 3). The 700R4 also needs its TV cable set up to work with an LS throttle, because the TV cable sets line pressure and a wrong setup burns the clutches. More: 700R4 TV cable bracket geometry.
- Manuals (TKX, T56 family, TR6060, T5): no controller, but you need an LS-specific bellhousing, clutch, flywheel and hydraulic release. The Tremec TKX is the most popular LS swap manual today; a T56 may need firewall or tunnel work to fit.
- ZF 8HP: it needs an adapter plate and a standalone transmission controller. Pick the controller before you buy the transmission, because support varies by 8HP generation and by the carmaker it came from. The adapter has to match your exact 8HP source.
Step 2: Check it can take your power
Match the transmission to your goal, not to the stock engine. From the ratings in our table:
| Transmission | What it's rated for |
|---|---|
| 4L60E | Stock about 300–360 lb-ft (about 300–400 hp on the street); built units about 450–500 hp |
| 4L80E / 4L85E | 440 lb-ft (MT1); 4L85E (MN8) 460 lb-ft: GM's factory engine-torque ratings. Built units and GM's SuperMatic 4L85-E crate version are sold with higher ratings; go by what the builder of your unit rates it for |
| T5 (World Class) | 300 lb-ft |
| Tremec TKX | 600 lb-ft |
| Tremec Magnum family | 700 lb-ft |
Whether a 4L60E will hold up to more power came up in 10 of the forum questions. Compare its numbers above to your target before you buy, especially if boost is in the plan.
Step 3: Get the flexplate and converter right (automatics)
This is simple once you see why it matters: the LS keeps the old small-block's bellhousing dowels and 5 of its 6 bolt holes, but the crankshaft flange sits farther forward. So what goes between the crank and the converter depends on the transmission:
- 4L60E (LS version): 11.062 in. converter bolt pattern. LS-version 4L60Es use a 300 mm input shaft and an LS converter.
- 4L80E: 11.5 in. converter pattern, so it needs a 4L80E-pattern flexplate.
- TH400: also the 11.5 in. pattern, the same as an LS that came with a 4L80E. Space the factory 4L80E flexplate out with an adapter.
- TH350, 700R4, Powerglide: most LS cranks sit about 0.400 in. shorter than older GM engines. Use a dished (or dual-pattern) flexplate with the 10.75 in. converter pattern, plus a converter adapter sleeve.
The exception that catches people: 1999–2000 LQ4 6.0s have a "long" crank flange. They take a flat flexplate with no dish or spacer. Behind one of those, a TH350 works with a TH400 converter, but a 700R4 has no easy fix short of a 2001-or-later crank.
If you're not sure which crank you have, go by the engine's year and code in the engine finder.
Step 4: Plan the crossmember, driveshaft and mounts
Changing the transmission moves the mounting point and the output shaft.
- Crossmember: plan on a transmission crossmember that fits your engine and transmission combination. It sets where the transmission mount sits, and with it the driveline angle. Check your vehicle's swap guide for kits we've sourced for it. More: getting driveline angles right.
- Driveshaft: don't plan on reusing the original. The engine and transmission usually sit about 3° down at the back, with the pinion set to match so the U-joint angles cancel. Measure for length with the engine and transmission in their final position. More: driveshaft and driveline angles
- Avoid the LS4 for rear-wheel drive: the 2005–2009 front-drive Impala SS/Monte Carlo SS/Grand Prix GXP engine uses a different bellhousing bolt pattern, among other problems.
Step 5: Make it shift
Before first start, confirm the transmission's control is sorted: the computer for an electronic unit (and a tune that knows about it), the TV cable on a 700R4, or the clutch hydraulics on a manual. The tune checklist covers what the computer side needs. More: transmission tuning for an LS swap.
Ratings, fitment notes and controllers for every transmission are in the tables below. Found something that doesn't match your experience? Tell us.
Every transmission compared
| Transmission | Type | Gears | RPO | Torque rating | Bellhousing | LS fitment | Controller | Used |
|---|---|---|---|---|---|---|---|---|
| 4L60E | auto | 4 | M30 | Stock ≈300–360 lb-ft (≈300–400 hp street); built street units ≈450–500 hp; fully re-engineered 800+ hp | GM V8 bellhousing pattern; bolt-on removable bellhousing on 1996+ cases; 1998+ LS (Gen III) versions use a 300 mm converter, 300 mm-style input shaft and pump (non-LS units used 298 mm) | GM LS-family bellhousing; LS versions use 300 mm input shaft / LS converter (non-LS 298 mm) | Factory GM PCM, or Holley Terminator X Max (built-in 4L60/4L80 control) | Used 4L60Es |
| 4L80E | auto | 4 | MT1 | 440 lb-ft (MT1); 4L85E (MN8) 460 lb-ft | Bellhousing is cast into the factory case (GM V8 / LS bolt pattern). A removable aftermarket bell needs an aftermarket case or a machined conversion of the factory case. | GM LS-family bellhousing | Factory GM PCM, or Holley Terminator X Max (built-in 4L60/4L80 control) | Used 4L80Es |
| 6L80 / 6L90 | auto | 6 | Not confirmed | GM LS-family bellhousing | Factory GM ECU/TCM, or Holley Terminator X Max + 558-499 6L80/6L90 kit (2WD only; needs Holley V3 software, build 100 or later) | Used 6L80Es | ||
| 8L45 | auto | 8 | M5N / N8R | Max engine torque 275 lb-ft; max gearbox torque 406 lb-ft (550 Nm) | 2-piece main case with the bell integrated into the main case (non-removable bellhousing); die-cast aluminum. | GM bellhousing | Used 8L45s | |
| 8L90 | auto | 8 | M5U (8L80: MFC/N8X) | 900 Nm (~664 lb-ft) max gearbox torque (GM estimate); 420 bhp max engine power | 2-piece main case with the bell integrated into the main case (non-removable bellhousing); die-cast aluminum. | GM bellhousing (LS/LT family) | Needs GM TCM/ECM support or standalone controller | Used 8L90s |
| ZF 8HP70 | auto | 8 | 8HP70/75 family ≈ 700–750 Nm factory (ZF); often run well above with torque management | No removable bellhousing — bell is integral to the case; Dodge/Ram 8HP70 donor units carry the Gen III Hemi bolt pattern, so an LS swap requires an adapter plate between block and case | Adapter required. Case/bellhousing is OEM-specific: kits exist for Ram/Hemi-pattern 8HP (e.g., LOJ) and for BMW-pattern 8HP (e.g., PMC Motorsport). Confirm the adapter matches your exact 8HP source (even two BMW 8HP70s can differ). | Standalone TCU required; choose the TCU before buying the transmission (support varies by 8HP generation and OEM; e.g., some controllers support Gen 1 8HP45/70/90 only). | ||
| 10L80 / 10L90 | auto | 10 | 10L80: MF6 (full-size SUV/truck applications); 10L90: MX0 (launch RPO, 2017 Camaro ZL1); 2017-2021 Camaro 10L90 also listed as RPO MI4. | 10L90: 650 lb-ft (GM SuperMatic rating). 10L80: not confirmed | GM bellhousing — standard SBC bolt pattern shared with Gen V LT (and LS) engines; 10L80/10L90 is the factory 10-speed for Gen V LT | GM bellhousing (10L); Ford 10R80 is a different case | Standalone controller or GM ECM support | Used 10L80s |
| T5 (World Class) | manual | 5 | MK6 (1988–92 F-body) | 300 lb-ft (WC with hardened 1st gear, from ~1990); Standard/NWC 265 lb-ft | Separate bolt-on bellhousing (not integral to the case); GM T5 cases use the standard GM (Muncie/Saginaw) 4-speed transmission bolt pattern | Found in S-10, Camaro/Firebird; LS use needs bellhousing/adapter | n/a | Used World Class T5s |
| Tremec TKX | manual | 5 | 600 lb-ft; 8,000 rpm capable, shifts at 7,500 rpm | Aftermarket; LS bellhousing required | n/a | |||
| TR6060 | manual | 6 | MG9 / MH3 | 430–650 lb-ft (580–880 Nm) max input torque, depending on gearing | GM LS/LT versions in Camaro SS/ZL1, Corvette C6, CTS-V, G8 GXP, Chevrolet SS | n/a — manual transmission; no electronic controller | Used TR6060s | |
| Tremec Magnum | manual | 6 | 700 lb-ft | No bellhousing included — Tremec application table lists 'Includes Housing: No' (GM TUET11009/11012, Ford TUET11010/11011) | Aftermarket; GM and Ford variants | n/a | ||
| Tremec Magnum-F | manual | 6 | 700 lb-ft (949 Nm) | Replaces T56 in 1998–2002 F-body; also for 1993–97 LT1 F-body (needs flywheel/clutch/slave changes) | n/a | |||
| Tremec Magnum-XL | manual | 6 | 700 lb-ft | No bellhousing included | GM variant available; includes SFI steel bellhousing, crossmember, trans mount, isolated shifter; reuses OEM hydraulic release | n/a |
T56 part numbers: identify a used T56
The T56 was built for GM, Ford, Dodge, Holden and Aston Martin. The tag number tells you which one you have; bellhousing, input shaft and shifter location differ. Sellers list them by the car they came out of, so shop by that, then check the tag before you pay.
| Part number | Originally for | Ratios | Torque | Bellhousing | Notes |
|---|---|---|---|---|---|
| 1386-000-003 | 1992 Dodge Viper | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 330 lb-ft | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 |
| 1386-000-005 | 1993–1995 Dodge Viper | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 550 lb-ft | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 |
| 1386-000-006 | 1993 Camaro/Firebird w/2.73 final drive "M28" | 3.36:1 / 2.07:1 / 1.35:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 350 lb-ft | Input splines 26, output 27 | |
| 1386-000-007 | 1993 Camaro/Firebird w/3.23 final drive "M29" | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 400 lb-ft | Input splines 26, output 27 | |
| 1386-000-009 | 1994–1995 Camaro/Firebird | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | Input splines 26, output 27 | |
| 1386-000-011 | GM Aftermarket | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 450 lb-ft | GM bolt pattern (sold as a GM aftermarket unit) | Input splines 26, output 27 |
| 1386-000-012 | Mustang 5.0 Aftermarket | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 450 lb-ft | Ford small-block bolt pattern (aftermarket Mustang 5.0 unit) | Input splines 10, output 31 |
| 1386-000-013 | Holden | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | GM/Holden bolt pattern (OEM Holden application) | Input splines 26, output 27 |
| 1386-000-014 | 1996–2002 Dodge Viper | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 | |
| 1386-000-016 | 1996–1997 Camaro/Firebird | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | Input splines 26, output 27 | |
| 1386-000-017 | 1998 Camaro/Firebird | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | Separate bolt-on bellhousing — 1998–2002 F-body uses the LS1-specific T56 bellhousing | Input splines 26, output 27 |
| 1386-000-018 | 1996–2002 Dodge Viper | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 |
| 1386-000-019 | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 390 lb-ft | |||
| 1386-000-020 | 1999–2002 Camaro/Firebird | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | Separate bolt-on bellhousing — 1998–2002 F-body uses the LS1-specific T56 bellhousing | Input splines 26, output 27 |
| 1386-000-021 | Aston Martin | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.79:1 / 0.63:1 / 2.90:1 | 450 lb-ft | Input splines 26, output 30 | |
| 1386-000-022 | Holden Commodore | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 350 lb-ft | GM/Holden bolt pattern (OEM Holden application) | Input splines 26, output 27 |
| 1386-000-023 | Corvette C5 (MM6) | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 375 lb-ft | No conventional bellhousing — C5 Corvette T56 is a rear transaxle on a torque-tube driveline | Input splines 26, output 27 |
| 1386-000-024 | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 375 lb-ft | |||
| 1386-000-025 | Corvette Z06 C5 (MZ6) | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.84:1 / 0.56:1 / 2.90:1 | 385 lb-ft | No conventional bellhousing — C5 Corvette T56 is a rear transaxle on a torque-tube driveline | Input splines 26, output 27 |
| TNET-1077 | 2.97:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 415 lb-ft | |||
| TNET-1247 | Dodge Viper | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 450 lb-ft | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 |
| TUET-1259 | 4.6 Mustang Aftermarket w/mech speedo | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 450 lb-ft | Ford modular 4.6L bolt pattern (aftermarket Mustang unit) | Input splines 10, output 31 |
| TUET-1260 | 4.6 Mustang Aftermarket w/elec speedo | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 450 lb-ft | Ford modular 4.6L bolt pattern (aftermarket Mustang unit) | Input splines 10, output 31 |
| TUET-1452 | Chevrolet Corvette | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 370 lb-ft | No conventional bellhousing — C5 Corvette T56 is a rear transaxle on a torque-tube driveline | Input splines 26, output 27 |
| TUET-1453 | Chevrolet Corvette | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 370 lb-ft | No conventional bellhousing — C5 Corvette T56 is a rear transaxle on a torque-tube driveline | Input splines 26, output 27 |
| TUET-1576 | Aston Martin | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.79:1 / 0.63:1 / 2.90:1 | 415 lb-ft | Input splines 26, output 30 | |
| TUET-1660 | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 350 lb-ft | Output splines 27 (input not listed in the source) | ||
| TUET-1694 | 2003–2004 Mustang Cobra | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.79:1 / 0.63:1 / 2.90:1 | 450 lb-ft | Ford bolt pattern (OEM Mustang Cobra application) | Input splines 10, output 27 |
| TUET-1806 | Dodge Viper SRT-10 | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 550 lb-ft | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 |
| TUET-2022 | Cadillac CTS-V | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.84:1 / 0.56:1 / 2.90:1 | GM bolt pattern (OEM Cadillac CTS-V application) | ||
| TUET-2060 | Mustang Cobra | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.80:1 / 0.62:1 / 3.28:1 | 450 lb-ft | Ford bolt pattern (OEM Mustang Cobra application) | Input splines 10, output 27 |
| TUET-2062 | Dodge Viper | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.74:1 / 0.50:1 / 2.90:1 | 550 lb-ft | Dodge Viper V10 bolt pattern (OEM Viper application) | Input splines 26, output 30 |
| TUET-2066 | Pontiac GTO/Holden Monaro | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.84:1 / 0.56:1 / 2.90:1 | GM bolt pattern (OEM Pontiac GTO/Holden Monaro application) | Input splines 26, output 27 | |
| TUET-5044 | Cadillac CTS-V (M12) | 2.97:1 / 2.07:1 / 1.43:1 / 1.00:1 / 0.84:1 / 0.56:1 / 2.90:1 | GM bolt pattern (OEM Cadillac CTS-V application) | ||
| TUET-6450 | T-56 Ford N/A XR6 | 3.35:1 / 2.07:1 / 1.35:1 / 1.00:1 / 0.80:1 / 0.63:1 | Ford bolt pattern (OEM Ford Falcon XR6 application) | Input splines 23, output 31 | |
| TUET-7477 | T-56 Magnum Chevy Aftermarket | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.80:1 / 0.63:1 | GM bolt pattern; aftermarket Magnum — bellhousing is application-specific and sold separately | Input splines 26, output 31 | |
| TUET-7484 | T-56 Magnum Ford Aftermarket | 2.66:1 / 1.78:1 / 1.30:1 / 1.00:1 / 0.80:1 / 0.63:1 | Ford bolt pattern; aftermarket Magnum — bellhousing is application-specific and sold separately | Input splines 26, output 31 | |
| TUET-8274 | T-56 Magnum Ford Aftermarket | 2.97:1 / 2.10:1 / 1.46:1 / 1.00:1 / 0.74:1 / 0.50:1 | Ford bolt pattern; aftermarket Magnum — bellhousing is application-specific and sold separately | Input splines 26, output 31 | |
| TUET-8277 | T-56 Magnum Chevy Aftermarket | 2.97:1 / 2.10:1 / 1.46:1 / 1.00:1 / 0.74:1 / 0.50:1 | GM bolt pattern; aftermarket Magnum — bellhousing is application-specific and sold separately | Input splines 26, output 31 |
Transmission controllers
| Controller | Kind | Controls | Transmissions | DBW | Notes |
|---|---|---|---|---|---|
| Factory GM ECU/PCM (junkyard) | Factory GM computer | Engine + the electronic transmission it was paired with | Matches donor (e.g., 4L60E/4L80E with Gen III truck PCMs) | Cheap, often comes with a junkyard engine; needs a standalone harness (bought from ~$500, e.g., BP Automotive, Speartech, PSI, Howell, or built from the donor harness) plus tuning. DIY total can be ~$400 if you already own ECU/software. Each GM ECU is designed for a specific vehicle/engine/trans combo. | |
| Holley Terminator X | Aftermarket ECU | Engine only | No | Self-learning EFI; better suited than a GM ECU for heavily modified or boosted engines. | |
| Holley Terminator X Max | Aftermarket ECU | Engine + drive-by-wire + electronic transmission | 4L60E / 4L80E built in; 6L80 / 6L90 with Holley 558-499 transmission kit (2WD only; needs Holley V3 software, build 100 or later) | Yes | Includes engine and transmission harnesses. V3 software adds 6L80/6L90 control via separate harness kit. |
| Standalone 8HP TCU (TurboLamik, CANTCU, etc.) | Standalone trans controller | ZF 8HP transmission | ZF 8HP (support varies by generation/OEM) | Choose TCU before buying the transmission. |
Transmission questions
- Best transmission for an LS swap
- Best manual transmission for an LS swap
- Will a 4L60E bolt up to a 5.3 or 6.0?
- ZF 8HP70 swap behind an LS
- How much horsepower can a 4L60E handle?
- Will a 4L60E bolt to a small block 350?
- How do you mate a 4L80E to an NP205 transfer case in a 72 K10, and how do you get VSS?
- How do I make a 700R4 survive behind an LS in a square body?
- What stall speed torque converter should I run behind an LS1/LS3/5.3 in an off-road rig with a TH400 or TH350?
- Will a 4L60E bolt up to an LQ4 6.0, and will it survive behind it?
- Should the transmission cooler run through the radiator or separately on an LS swap?
- Should I regear my high-mileage stock 10-bolt or save for a stronger rear end?