I own a 1979 F250 4X4. Recently I converted from manual to automatic transmission. I got the automatic and linkage including the steering column from a 1979 Bronco. I also got the different adapter to connect to C-6 to the NP205. When I finished, the Transfer case bolted in the same holes in the frame as it did with the manual. The 4 wheel drive lever also connected in the right spot. No need for a change in drive line lengths. Here is the problem I ran into. The front drive line has a C/V joint that connects at the Transfer Case. The second knuckle on the C/V joint hits the pan on the C-6. It will not make a revolution. Here is the question. Did Ford just put a U-joint on the front drive line when it was going to be automatic? Or is their a smaller C/V joint they used on automatics? Or there is always the third option. Have I missed something? I am driving the vehicle right now. Everything is working fine.

 

if your pinion angle isn't too severe, you should be able to get by with just a universal.

 

my 79 150(250) with it's c-6 and 205 has the cv on it, the same as my old manual tranny 250 did,which the axles for my 150 came from, just throwin brush on the fire


1985 F-150/351Ho/c6/4wd~94,000 miles
1979 F-150extcab4x4/460/c6/6inchlift w/60rear44frnt (250 axles and springs)
37 inch boggers

 

Well, that does make this problem more interesting. Any ideas what I have done wrong so that it won't fit? Like I said in my original post, everything bolted up in the same holes and it is working fine right now, but only in 2wd. I tried stopping at the parts department at a Ford dealership, but they were no help. If I could find a way to keep the c/v joint I would sure like to. The truck is not lifted now, but at some future point I might put a small lift on the truck to fit 35's (I currently run 33's). If I can't find a way I guess I spend $150 to have the c/v joint removed and the drive line lengthened.

 

Two more thing I just thought of. I know I am grasping for straws here. 1, Is there more than one style of NP205. If the front output yolk on the 205 was a little further away then I would not have clearance problems. 2, Is there more than one style adapter (shorter, longer) to bolt a c-6 to a 205? If there is and that is what I need then I would have to lenghten one and shorten the other drive line and get new linkage for the 4 wheel drive shifter. I would also have to have a different output shaft on the c-6.
Conversions are always fun.
Any help would be appreciated.

 

that is strange. My 77 has a 203, c-6, and the drive shaft has a cv on it. Can you post a pic of the problem? That doesn't make cents. Is the oil pan on the c-6 extra deep? maybe go with one that is more shallow or modifiy the oil pan you have to fit. Might be cheeper.

 

For those wondering what is going on. Here is what I have found out. I found a 1979 F250 4X4 with C-6 in town today. I asked the guy if I could take a look underneath (of course, after I had explained my predicament). Sure enough, his front drive line had a c/v joint in it. Here is what I found that really suprised me. The adapter on his was about 4 inches longer (I didn't have measuring tape, just estimating) than mine. This means the c/v joint has ended before it gets to the c-6. The rear drive line must be shorter and the front driveline must be longer on an automatic pickup. His transfer case bolted to the frame further back than mine. I bought my adapter on ebay. I guess there is more than one type of adapter. As is see it, I have two options. The first would be to do it right. I would have to take the c-6 out and take it apart and put in a longer output shaft (I have one). Then I would have to find a longer adapter. Put it all back in and then have the front drive line lengthened and the rear drive line shortened. Then I would have to find new linkage for the four wheel drive shifter.
The second option is to say screw all that work and have the c/v joint removed and put a u-joint on the front driveline and lengthen it. The second sounds a lot easier. Interesting predicament.

 

Brek, if you are looking for an easy and cheap fix, I think I would look at the tranny pan. How about getting an extra pan from the salvage yard and cutting away the portion that interfears with your shaft, and welding some sheet metal over your cut-out. If it works it would be alot easier than either of your other fixing ideas. If it can't be made to work a tranny pan from the scrap yard is a very inexspensive experiment. DF

 

Ford did make two different adapters one was an 8" and the other was a 5". There is also two different lengths of tail shafts on the C6. If yours came off of a Bronco then I would guess you probably have the C6 with the short tail shaft. I would find another truck (the same as yours) get out your measuring tape and measure the overall length of the transmission and adapter. If the C6 and adapters are correct the drive shafts should work.

 

Again I agree with dinosaurfan. Fix the tranny pan. Much easier and cheeper as far as time spent.

 

I apologize. I don't think I explained how the c/v joint was rubbing the transmission good enough. It rubs the pan on the lip where it bolts to the transmission. I would have to cut not only the transmission pan, but also the transmission to make it fit.
I just have the wrong adapter to be able to fit a c/v joint. If I had the longer adapter the c/v joint would end before it got to the transmission.
I am pretty confident I don't have the money or the motivation to take it apart again and do it right. I think the u-joint will work in the place of a c/v joint if I don't do any major lifting of the vehicle.
I appreciate everyones input. If there are any more ideas I would like to hear them, as well as any reasons why you think I should not use just a u-joint at the transfer case.

 

you do run the risk of going through the trouble of replacing the cv with a u and having the angle be too much and it not working. Then you would have to change out the adaptor and re-work the joint again...I know it is a pain in the butt...the choice is yours.

 

Don't give up!! If you don't have the money or time then run it as a two wheel drive until you can come up with the money and time. It is a great old truck and if you are going to do the job then try, and if at all possible do it right. If you start modifying you don't know if it will work or not until you make the modification and then it may be wasted effort and money all over again.
I know is not what you want to hear, but in the long run you will be more happy if it is done right.

 

Sweeet Salvation -I've got one more input. My 78 F-250 is running a single u-joint on the front of the transfer case as we speak. That's how it was when I got it, and it run fine now. It is stock ride height I might add.
Good luck, it sounds like you need it.

 

with all these post...lets us know what you decide to do.

happy truckin'