The usual Cummins swap transmission options are the Dodge automatics that came behind the engine, the 47RE and 48RE four-speeds and the 68RFE six-speed; GM’s Allison 1000 with adapter parts; and heavy-duty manuals such as the NV4500, NV5600 and G56. The right choice depends on the engine version, power level, how much electronic control you are willing to set up and the vehicle. Mechanical 12-valve engines pair simply with manuals; any electronically controlled automatic needs a matching controller.
Cummins swap transmission options
| Transmission | Type | Notes | From in our range |
|---|---|---|---|
| 47RE | 4-speed automatic | Throttle valve cable and governor control; behind the 5.9 in 1990s and early 2000s Rams | $2,799.00 |
| 48RE | 4-speed automatic | Electronic throttle valve actuator; behind 2003 to 2007 5.9s | $4,099.00 |
| 68RFE | 6-speed automatic | Fully electronic; behind the 6.7 in Rams | $4,299.00 |
| Allison 1000 | 5- or 6-speed automatic | Needs adapter parts and a controller | $5,625.00 |
| NV4500, NV5600, G56 | Manual | Clutch, bell housing and hydraulics required | Not listed |
Matching the transmission to the engine
- 12-valve 5.9: a mechanical engine with no computer to run the 47RE’s electronic overdrive, lockup and governor functions, so a swap needs a stand-alone transmission controller, or a manual.
- 24-valve and common-rail 5.9: the original 47RE or 48RE is the straightforward match.
- 6.7: the 68RFE is the factory pairing; other choices need more electronic work.
See 12-valve vs 24-valve vs common rail and 5.9 vs 6.7 Cummins.
Strength and towing
Factory automatics were built for factory power. Heavy towing and added power shorten their life, so budget for a cooler and a heavy-duty unit if you plan big loads; see 47RE problems, 48RE problems, 68RFE problems and Allison 1000 problems.
Automatic or manual?
Automatics suit towing, traffic and drivers who want the truck to do the work, and the factory Dodge automatics are the most straightforward fit. Manuals avoid transmission electronics and torque converter heat, and many swappers prefer them behind high-power or mechanical engines, but they add clutch hydraulics and need a bell housing and clutch suited to diesel torque.
Swapping into a non-Dodge vehicle
In Ford or GM trucks and older vehicles, mounts, crossmember position, driveshaft length, transfer case compatibility and speedometer signals all need attention. Plan the driveline before buying the transmission.
Swap checklist
- Bell housing, adapter and flexplate or flywheel to match engine and transmission
- Transmission control for electronic units
- Crossmember, mounts and driveshafts
- Cooler and lines sized for towing; see transmission cooler
Related
See Cummins swap, 47RE vs 48RE, 48RE vs 68RFE, Cummins engines and our Dodge and Ram transmissions.
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