The 68RFE and the Allison 1000 are the automatic transmissions behind two of the most familiar heavy-duty diesels: the 68RFE in Ram 2500 and 3500 trucks with the 6.7 Cummins from 2007.5, and the Allison 1000 in GM heavy-duty trucks with the Duramax diesel from 2001. The Allison has a long reputation for durability under towing; the 68RFE does the job in unmodified and lightly modified trucks but has well-known weak points. They are not interchangeable between the two makes of truck.
68RFE vs Allison 1000 at a glance
| 68RFE | Allison 1000 | |
|---|---|---|
| Trucks | Ram 2500/3500 with the 6.7 Cummins | GM 2500/3500 HD with the Duramax and some gas engines |
| Gears | 6 | 5 in early years, then 6 |
| Gear ratios | 3.23 / 1.84 / 1.41 / 1.00 / 0.82 / 0.63 | 3.10 / 1.81 / 1.41 / 1.00 / 0.71 (6-speed adds 0.61) |
| Fluid | ATF+4 | Allison-approved fluid or the Dexron GM specifies |
Durability
The Allison 1000 is widely regarded as tough under heavy towing in factory form. The 68RFE’s reported weak points include overheating, torque converter and clutch wear under heavy loads and added power, and valve body issues; see 68RFE problems and Allison 1000 problems. Both last longest with fresh fluid, a healthy cooler and sensible towing habits.
Towing habits that help both
- Use tow/haul mode when towing so the transmission holds gears and avoids hunting.
- Watch transmission temperature if your truck displays it, and back off on long grades when it climbs.
- Shorten the fluid and filter service interval if you tow often.
- Keep the cooler clean and the cooling system healthy.
See transmission overheating for the warning signs. Added power raises the load on either transmission, so a stronger converter and clutches are worth considering if the engine has been modified.
The Aisin option on Rams
Ram 3500 high-output trucks offered the Aisin AS69RC as an alternative to the 68RFE; see 68RFE vs Aisin.
Choosing a truck or a replacement
If you are shopping for a used truck, the transmission’s service history matters more than the model. If you are replacing a failed unit, a heavier-duty build is worth considering for frequent towing or added power. For the engines themselves, see Cummins vs Duramax vs Powerstroke.
Replacement units we list
- RoadReady Dodge 68RFE: $4,299.00
- StreetMonster Dodge 68RFE: $4,899.00
- SportMonster Dodge 68RFE: $7,194.95
- SportMonster Chevy Allison 1000: $5,625.00
Each includes a torque converter. Browse 68RFE transmissions and Allison 1000 transmissions.
More guides: 66RFE vs 68RFE · 6L90 vs Allison 1000 · how long a 68RFE lasts · how long an Allison 1000 lasts.
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