Fitment guide
Which transmission goes with an LS1, LS2, LS3, LS7 or LS9?
Factory torque, the transmission each engine came with, and where a 4L60E-family or 4L80E fits in a swap.
Short answer
Match the transmission to engine torque. A stock LS1 (about 350-365 lb-ft) sits at a 4L60E's rating; an LS2 or LS3 (400-424 lb-ft) points to a 4L65E/4L70E or 4L80E; an LS7 (470 lb-ft) or LS9 (604 lb-ft) is beyond a stock 4L80E's 440 lb-ft rating and needs a built unit rated for it.
How do the LS1, LS2, LS3, LS7 and LS9 compare?
| Engine | Displacement | Factory output | Factory transmissions (examples) | Common swap automatic |
|---|---|---|---|---|
| LS1 | 5.7 L | 345-350 hp / 350-365 lb-ft (Corvette) | 4L60E or T56 (Corvette, Camaro, Firebird) | 4L60E family |
| LS2 | 6.0 L | 400 hp / 400 lb-ft | 4L65E or T56 (Corvette, GTO) | 4L65E / 4L70E or 4L80E |
| LS3 | 6.2 L | 430 hp / 424 lb-ft | 6L80 or TR6060 (Corvette) | 4L70E or 4L80E |
| LS7 | 7.0 L | 505 hp / 470 lb-ft | Six-speed manual only (Corvette Z06) | Built 4L80E |
| LS9 | 6.2 L supercharged | 638 hp / 604 lb-ft | Six-speed manual only (Corvette ZR1) | Built 4L80E |
Engine output from JEGS; factory transmission pairings from G Force Performance. Transmission ratings: 4L80E 440 lb-ft (GM, via LSSwapBible); stock 4L60E about 360 lb-ft, with the 4L65E and 4L70E rated higher. Your engine's real torque depends on cam, intake, tune and boost, so use your own number.
What transmission goes with an LS1?
The 4L60E. GM paired the LS1 with the 4L60E (or a T56 manual), and a stock LS1's 350-365 lb-ft sits right around a stock 4L60E's rating. For a near-stock LS1 in an older car, a healthy 4L60E-family unit is the usual pick. If you're adding a cam, heads and a tune, consider a 4L65E/4L70E or a built 4L60E. Either way, our 1998-and-newer 4L60E speed kit ($850) or 4L60E tail housing kit ($850) keeps the factory speedometer.
What transmission goes with an LS2?
A 4L65E, 4L70E or 4L80E. The LS2's 400 lb-ft is over a stock 4L60E's rating, which is why GM used the stronger 4L65E behind it. The 4L65E and 4L70E share the 4L60E's compact case, so our 4L60E/4L65E/4L70E kits fit them. If you want more margin, step up to a 4L80E and our 4L80E tail housing kit.
What transmission goes with an LS3?
A 4L70E or 4L80E for a 4-speed swap. In the Corvette, GM paired the LS3 with a 6-speed (6L80 automatic or TR6060 manual), but many older-car builds run a 4-speed electronic overdrive for its size and simpler controls. At 424 lb-ft stock, the LS3 is close to the 4L80E's 440 lb-ft rating, so a 4L80E or a 4L70E built for the job gives you some headroom.
What transmission goes with an LS7 or LS9?
A built 4L80E. GM only sold the LS7 (470 lb-ft) and the supercharged LS9 (604 lb-ft) with six-speed manuals, and both are past a stock 4L80E's 440 lb-ft rating. If you want an automatic behind one, buy a 4L80E or 4L85E built and rated for your torque. Our 4L80E tail housing kit ($900) is built for builds like this: a 4L80E behind a big-inch LS or a blown small block. The 4L80E speedometer kit ($900) is the other 4L80E option.
One note for LS9 owners: our carbon fiber LS engine cover fits every LS except the LS9.
Does the engine computer matter?
Yes. The 4L60E and 4L80E need a controller. A factory GM PCM matched to the donor, or an aftermarket ECU with 4L60E/4L80E control built in, are the common routes (LSSwapBible). Sort the controller before buying the transmission, especially when the engine came out of a car that had a 6-speed or a manual.
Can I keep a mechanical speedometer with any of these?
Yes. The speedometer drive lives on the transmission, not the engine, so the engine choice doesn't change it. Pick the kit for your transmission, then size the gears with the calculator. More in our mechanical speedometer guide and 4L60E vs 4L80E.
Frequently asked questions
What transmission came with the LS1?
GM paired the LS1 with the 4L60E automatic or the T56 six-speed manual in cars like the Corvette, Camaro and Firebird.
Can a 4L60E handle an LS3?
A stock 4L60E is rated around 360 lb-ft, while a stock LS3 makes 424 lb-ft, so most builders choose a 4L70E, a built 4L60E-family unit or a 4L80E (rated 440 lb-ft) behind an LS3.
What automatic transmission should I use with an LS7 or LS9?
A 4L80E or 4L85E built and rated for the engine's torque. The LS7 makes 470 lb-ft and the supercharged LS9 makes 604 lb-ft, both above a stock 4L80E's 440 lb-ft rating, and GM only sold them with six-speed manuals.
Does my LS engine choice affect the speedometer kit?
No. The speedometer drive is on the transmission's output shaft, so you pick the kit for your transmission (4L60E family or 4L80E) and size the gears for your tire diameter and rear axle ratio.
Talk to the shop
Every housing and speed kit is machined in Caddo Mills and ships with gears cut to your tire diameter and rear axle ratio. Questions about your combination? Call 903-527-2006, Monday to Friday, 7am–3pm Central, or email [email protected].
Shop the kitsGear calculatorSources
- JEGS: Complete LS engine specs and differences
- G Force Performance: GM transmissions for a Vortec or LS motor
- LSSwapBible: LS swap transmissions compared
- Street Muscle: Spotter's guide to the 4L60E (TCI length chart and ratings table)
Kit details come from Southwest Fabrication's own product listings. Outside technical figures are linked above; check them against your exact parts.
