Find A Transmission
TH350
Ratios: 2.52 / 1.52 / 1.00
Architecture: No overdrive • no lockup in the classic TH350 configuration
Controls: Simple hydraulic 3-speed; no PCM/TCM required.
LS-swap watch list: LS swaps need the correct flexplate/converter spacing and a suitable kickdown/detent-cable arrangement.
LS Truck Labs field guide: Compact traditional choice for light/simple builds; highway rpm is dictated by 1:1 top gear and axle/tire choice.
TH400
Ratios: 2.48 / 1.48 / 1.00
Architecture: No overdrive • heavy-duty legacy architecture
Controls: Hydraulic shifting; electric kickdown switch on traditional applications, not electronic shift control.
LS-swap watch list: LS swaps require converter/flexplate spacing, crossmember/driveshaft planning and cooler plumbing.
LS Truck Labs field guide: Classic heavy-duty option; gives up overdrive and has a less aggressive first gear than 4L60/6L families.
700R4 / 4L60
Ratios: 3.06 / 1.63 / 1.00 / 0.70
Architecture: Deep first • 30% overdrive
Controls: Hydraulic TV cable controls critical line-pressure/shift behavior; converter lockup is electrical/hydraulic depending on setup.
LS-swap watch list: TV geometry is not optional detail: incorrect setup can damage the transmission. Plan lockup control, converter, driveshaft and crossmember.
LS Truck Labs field guide: Useful pre-electronic overdrive choice when a build needs highway gearing without a transmission controller.
4L60E
Ratios: 3.06 / 1.62 / 1.00 / 0.70
Architecture: PCM-controlled shifts + TCC
Controls: Electronic shift solenoids and PCM strategy control shift timing/feel and converter clutch.
LS-swap watch list: Match transmission generation, connector/controller strategy, converter, flexplate spacing, VSS, crossmember and driveshaft.
LS Truck Labs field guide: Common LS-era light-duty transmission; diagnose mechanical capacity and calibration separately rather than treating pressure tables as a hardware repair.
4L65E / 4L70E
Ratios: 3.06 / 1.62 / 1.00 / 0.70
Architecture: Same basic ratios as 4L60E family
Controls: Electronic controls; specific internal hardware and calibration vary by version/application.
LS-swap watch list: Verify exact transmission ID and controller compatibility before buying swap parts.
LS Truck Labs field guide: Chevrolet Performance currently publishes 430 lb-ft for its SuperMatic 4L65-E and 495 lb-ft for its SuperMatic 4L70-E; those ratings describe those performance units, not every production core.
4L80E / 4L85E
Ratios: 2.48 / 1.48 / 1.00 / 0.75
Architecture: HD architecture • electronic control
Controls: Requires compatible electronic control for commanded shifts and TCC.
LS-swap watch list: Plan converter/flexplate spacing, cooler fittings, wiring/controller, crossmember, driveshaft/yoke and calibration.
LS Truck Labs field guide: Chevrolet Performance documentation distinguishes the families primarily by gearset design/capacity; its catalog notes four-pinion 4L80-E vs five-pinion 4L85-E while external mounting provisions are identical.
6L80E / 6L90E
Ratios: 4.03 / 2.36 / 1.53 / 1.15 / 0.85 / 0.67
Architecture: Very deep first • two overdrives
Controls: Integrated modern electronic control; shift scheduling, torque management and TCC behavior interact.
LS-swap watch list: Controller/ECM compatibility, transmission generation, converter, shifter/range input, VSS, driveshaft and calibration all matter.
LS Truck Labs field guide: Excellent ratio spread for trucks. Do not apply Chevrolet Performance SuperMatic capacity claims to every production 6L80/6L90.
T56
Ratios: Application-dependent
Architecture: Double-overdrive manual; OEM ratios vary by application
Controls: No automatic shift control; swap still needs speed signal/reverse/skip-shift considerations as applicable.
LS-swap watch list: Bellhousing, input length, clutch/flywheel, pilot bearing, hydraulic release, shifter location, crossmember and driveshaft must work as a system.
LS Truck Labs field guide: Treat “T56” as a family name, not one universal ratio/capacity specification.
T56 Magnum / Super Magnum
Ratios: 2.66-based or 2.97-based sets
Architecture: Aftermarket TR-6060-derived architecture
Controls: Manual transmission; multiple shifter/speed-pickup provisions depend on Magnum version.
LS-swap watch list: Choose the ratio set and shifter location for the truck, then match bellhousing, clutch/hydraulics, yoke and driveshaft.
LS Truck Labs field guide: TREMEC rates Magnum at 700 lb-ft and offers 2.66- or 2.97-first ratio sets. Chevrolet Performance Super Magnum publishes 2.66 / 1.78 / 1.30 / 1.00 / 0.80 / 0.63.
Ratio Comparison
| Family | 1st | 2nd | 3rd | 4th | 5th | 6th | Control |
|---|---|---|---|---|---|---|---|
| TH350 | 2.52 | 1.52 | 1.00 | — | — | — | Hydraulic |
| TH400 | 2.48 | 1.48 | 1.00 | — | — | — | Hydraulic |
| 700R4 / 4L60 | 3.06 | 1.63 | 1.00 | 0.70 | — | — | Hydraulic + lockup |
| 4L60E / 65E / 70E | 3.06 | 1.62 | 1.00 | 0.70 | — | — | Electronic |
| 4L80E / 85E | 2.48 | 1.48 | 1.00 | 0.75 | — | — | Electronic |
| 6L80 | 4.03* | 2.36 | 1.53 | 1.15 | 0.85 | 0.67 | Electronic |
| Super Magnum | 2.66 | 1.78 | 1.30 | 1.00 | 0.80 | 0.63 | Manual |
*GM production documentation commonly publishes 4.03 for the 6L80; Chevrolet Performance currently rounds its SuperMatic listing to 4.02. Use the exact application data when precision matters.
Choose By System, Not By Reputation
A transmission swap is more than bellhousing bolt pattern. Compare overall gearing, truck weight/use, engine torque curve, converter or clutch, controller compatibility, driveshaft/yoke, crossmember, shifter/range input, speed signal, cooler capacity and calibration. A transmission that is “stronger” on paper can still be a worse match if the ratio spread or integration fights the rest of the truck.