The 545RFE and 68RFE are both electronically controlled Chrysler automatics, but for different trucks. The 545RFE is the light-duty five-speed used behind V8s in Ram 1500, Dakota, Durango and Jeep models, with an alternate second gear for smoother kickdowns. The 68RFE is the heavy-duty six-speed behind the 6.7L Cummins in Ram 2500 and 3500 trucks. They are not interchangeable: size, bellhousing, converter and strength are different.
545RFE vs 68RFE at a glance
| 545RFE | 68RFE | |
|---|---|---|
| Duty | Light duty | Heavy duty |
| Gears | 5, plus an alternate second | 6 |
| Typical vehicles | Ram 1500, Dakota, Durango, Jeep Grand Cherokee and Commander | Ram 2500 and 3500 with the 6.7L Cummins |
| Control | Fully electronic | Fully electronic |
| Fluid | ATF+4 | ATF+4 |
The alternate second gear
The 545RFE can use a second ratio between first and third on kickdown, which smooths the downshift. That is why it is sometimes described as having six forward ratios even though it is called a five-speed.
Limp mode on RFE transmissions
Both transmissions protect themselves by going into limp mode, usually holding second gear, when the computer sees a fault such as a solenoid, sensor or pressure problem. Limp mode does not always mean the transmission is worn. Read the codes first: a failing solenoid pack, range sensor, speed sensor or a low battery voltage can trigger it, and fixing those costs far less than a replacement. If limp mode comes with burnt fluid and slipping, the internals are likely worn.
What came before
The 545RFE replaced the four-speed 46RE in light-duty applications, and the 68RFE replaced the 48RE behind the Cummins; see 46RE vs 47RE and 48RE vs 68RFE.
Towing with a 545RFE truck
A 545RFE in a Ram 1500 or Durango is built for the loads those vehicles are rated for. You cannot upgrade a half-ton to a 68RFE, since the engines and bellhousings differ, so stay within the vehicle’s towing rating, use tow/haul mode and consider an auxiliary cooler if you tow often. If the transmission runs hot or shifts poorly when loaded, check the fluid level and condition first; see transmission overheating and how to check transmission fluid.
Common problems
- 545RFE: limp mode, valve body and solenoid faults, and overdrive problems; see 545RFE problems.
- 68RFE: overheating with heavy towing, clutch and converter wear, valve body issues; see 68RFE problems.
Both depend on a healthy solenoid pack and clean fluid; see transmission solenoid pack and limp mode.
To confirm your code, check the build data or the identification tag on the transmission; see what transmission do I have?
Replacement units we list
- RoadReady Dodge 545RFE: $3,099.00
- RoadReady Dodge 68RFE: $4,299.00
- StreetMonster Dodge 68RFE: $4,899.00
Each includes a torque converter. Browse 545RFE transmissions and 68RFE transmissions.
More guides: 66RFE vs 68RFE.
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