65RFE in a Dak?

Thanks for the info. A bit more net searching and I found that the 45RFE can perform just like the 545RFE with only a TCM change, pretty cool. But I think the 65RFE is a bit more than just a TCM change, not sure. Like you say it may involve different communication on the BUS. Would be awesome though if someone could make a 65RFE perform with the 4.7 in a way to get 20+ mpg on the highway.

I once had a 2006 Ford Explorer for a company vehicle. It had the 5.0V8 teamed with a 6-speed automatic. On the highway at steady 70 mph and fairly flat terrain that bog ol 300hp V8 was getting 24 mpg, I think with a 3:55 rear axle ratio or slightly lower. Pretty impressive.

Primus said:

It's hard to say whether if just the software change is all that allows the 6spd. to be accessible on the older RFE's, as the fact the transmission is still the same and there was not much changed internally from the first model year they were available to the last year before the ZF 8HP became the only automatic in the Ram's, Durango's, and the JGC's.
You will probably have better luck looking into this from the factory service manuals for the years the 65RFE was available, then start comparing connections and then the BUS comms to see if the Dakota's and Durango's with the RFE can work with these.

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My goal is to use my 2001 Dakota as the frame/drivetrain/interior donor for the 56 C3 pickupI bought. My Dak has a 5spd manual but I'll go with the automatic 5spd or 6spd, maybe with a 3:21 rear axle ratio. I plan to use a remanufactured 4.7 HO long block, with headers and TB updates to get over 310 crank HP. Plenty enough for my driving. If that ZF tranny would connect to the 4.7 I'd consider that for sure.

Right, I'd assume the same. The biggest difference between the ratios of a 65RFE and ZF 8HP are 1st gear and top gear. 1st ratio is 4:00 in the ZF versus 3:71 in the RFE. But top gear is the same for both; 062, so steady highway speed engine RPM would be the same with either trans. But I wonder if a 545RFE can be updated to a 65RFE with a TCM and torque converter change?

Interesting info. I'll have to study more to determine if the 545RFE or the 65RFE is the right trans to work with my 4.7 engine build. Plus, I plan to use either an American Shifter or Lokar floor console shifter for both auto and manual shifting control.