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I recently purchased a 1972 COE with a 391 engine. It is a stick shift and I would like to replace it with an automatic transmission. I am also going to replace the rear axel with something smaller. Any advise or suggestions on what transmission I should be looking for will be greatly appreciated. Thanks!
Welcome. I had to look up what a COE was. Looks like a medium/heavy duty cab over. As far as automatic transmissions go, the C6 is the only thing that will bolt on. The 391FT shares the same bell housing bolt pattern as the FE motors. Something I read said that the C6 was never used on the FT motors. Depending on how you will be using it might decide that. There would plenty of adapter plate/tranny type swaps. Sky is the limit. Got any pictures of the truck? You will need some more posts for that though. What are you thinking about doing with the rear axle, down sizing?
Yes, I plan on down sizing the rear end. I am probably going to try and find a rear end out of a 1 ton truck from the 80's or 90's. The truck will be getting lowered and will not be used as a work truck anymore. Do you know what year range of C6 I should be looking for? I will try and post some pictures tomorrow.
1976 was the last year of the FE motors in the trucks. So, 76 and earlier. There will probably be a lot of fabricating of some things switching one of those over to A/T. Not sure how that would work with the steering column. Are you staying with dually rear end? There is also the dana70. What part of the country are you located?
1976 was the last year of the FE motors in the trucks. So, 76 and earlier. There will probably be a lot of fabricating of some things switching one of those over to A/T. Not sure how that would work with the steering column. Are you staying with dually rear end? There is also the dana70. What part of the country are you located?
Is that 391 internal or externally balanced, that would be my only question. Since you are looking to change the rear axle, would it make more sense to drop the COE Cab onto a newer chassis? Just a thought, upgraded engine, trans, steering, brakes and suspension that way.
Is that 391 internal or externally balanced, that would be my only question. Since you are looking to change the rear axle, would it make more sense to drop the COE Cab onto a newer chassis? Just a thought, upgraded engine, trans, steering, brakes and suspension that way.
I have no idea on the balanced question. I have played with the idea, however it's a large cab and would be a ton of fan work to put it on something else. I thing taking out most of the leaf springs and adding air bags will be "easier"
I would dump the 391FT, and as a minimum go with a 390 FE due to parts availability. With a C series made from 57-90, you have a lot of options available. Since it used the 370/429 79-90, why not a 460 as engine supports would be readily available, plus with an E4OD (C-6 class) 4 speed available for a trans.
E = 361 2V FT gas V8. If it is a 391, it will be a 4V and it's a replacement engine.
V = Kentucky Truck Plant
J45129 = 1970 numerical series, June 1970 production.
What does your title say? You may want to look for the VIN on the passenger side of the frame, top of the rail or top of bottom rail.
Engine balance:
330HD, 361 and 391 are external balance. So you can't use an FE flexplate.
C series usually isn't called a COE, but rather a Tilt Cab. The COE had a big dog house and was a torture device when working on the engine, vs. the day at the beach with the C series tipping that cab up and way.
FT engines are slow reving engines made for slogging along with heavy loads. Most are governed to 3800 RPM. Heavy pistons and small intake valves figure in the mix as well.
As to popping a 460 in there, the 370/429 are certainly related to the 460, but they mount differently. They mount just like the FT motor, using a single mount off a steel or cast front cover, and one mount on each side of the bell housing out back.
So you would need to bring or fabricate mounts for the 460. A 460/E4OD would be a good combo, but you would need a controller for the E4OD. E4OD has some design features in common with the C6 but is a completely different transmission overall. It is NOT a C6 with an overdrive unit on it, a falsehood often repeated.
Popping the C series cab on a rolling chassis might work, but the challenges will be there when it comes to control location vs. driver position. (That's what U-joints are for....)