C-6 combinations, will 78 F-150 fit 72 F-250?

Kurt Combs · Post by **Kurt Combs** » Thu Feb 09, 2012 10:31 pm

As I mentioned in a previous post, I am buying a 1978 F-150 with a 460 and a C-6 to replace the 360 and C-6 in my 72 F-250. Both are two wheel drive, but the 72 has a two piece drive shaft and the 78 has a one piece shaft. Talked to the local transmission shop today and one of the mechanics said I could use the drive shaft out of the 78 in the 72 because the donor C-6 has a long tail shaft and I could just remove the center support. The other option would be to have them put the short tail shaft off my existing C-6 on the donor transmission. I hate to disassemble the donor transmission considering it was just rebuilt, but I want the best result I can have with the fewest problems, so I am leaning towards changing the tail shaft. (Or I could rebuild the 390 in my shop and forget the 460.) Any comments on what am I getting myself into? Is this tail shaft swap as easy as the transmission guy says it is?

Post by **70_F100** » Fri Feb 10, 2012 6:29 am

In the grand scheme of things, it will probably be MUCH easier to swap out the tailshaft.

Otherwise, you're looking at frankensteining the driveline.

red403 · Post by **red403** » Sat Feb 11, 2012 2:02 am

If you are using the motor,transmission from the donor truck why not use the driveshaft also? Dad had a friend that had a 77 with a 460 c6 and I am sure it had a one piece drive shaft and he didn't have any problems with his.

Post by **70_F100** » Sat Feb 11, 2012 9:09 am

red403 wrote:If you are using the motor,transmission from the donor truck why not use the driveshaft also? Dad had a friend that had a 77 with a 460 c6 and I am sure it had a one piece drive shaft and he didn't have any problems with his.

Yep, some, if not all of the later model LWB pickups used a one-piece driveline.

However, 73-up dentsides were 2" longer than the bumps, and the extra inches were added behind the tranny. That would make the driveline 2" longer.

That may not be an issue here, but by changing the tailshaft, you can be sure the driveline will work because the rear of the transmission will be at the same place it was with the 360 combo and everything should be a bolt-in installation.

Hawkrod · Post by **Hawkrod** » Sat Feb 18, 2012 10:18 am

70_F100 wrote:
red403 wrote:If you are using the motor,transmission from the donor truck why not use the driveshaft also? Dad had a friend that had a 77 with a 460 c6 and I am sure it had a one piece drive shaft and he didn't have any problems with his.
Yep, some, if not all of the later model LWB pickups used a one-piece driveline.

However, 73-up dentsides were 2" longer than the bumps, and the extra inches were added behind the tranny. That would make the driveline 2" longer.

That may not be an issue here, but by changing the tailshaft, you can be sure the driveline will work because the rear of the transmission will be at the same place it was with the 360 combo and everything should be a bolt-in installation.

I would point out that very few of the dents use a 1 piece shaft. The 1 piece shaft was only used on cheap low GVWR applications and all the heavier trucks had two piece shafts even if it had a trans with a slip yoke (I know, it seems so wrong). It is fine for what it is designed for and you can have it shortened to fit an earlier truck but in this case it may be better to have teh new shaft adapted to the old front shaft. It is cheap and easy. Hawkrod

Kurt Combs · Post by **Kurt Combs** » Sat Feb 18, 2012 10:29 am

Well this is interesting. I assumed it had a one piece because when looking at the truck at the college shop we discovered the drive shaft was missing and "someone saw the night instructor walking around with a drive shaft," but that is not unusual and it was decided that it was a shaft they always use for demonstrations. Later it was discovered that he had taken the shaft out of the F150 and he subsequently returned it. It just seemed like too much work to remove a two piece shaft for a demonstration, so I assumed it had a one piece. When I get the truck I will have to take a look and see what it has before deciding on what to change. Thanks for all the input everyone.

Hawkrod · Post by **Hawkrod** » Sat Feb 18, 2012 10:41 am

Kurt Combs wrote:Well this is interesting. I assumed it had a one piece because when looking at the truck at the college shop we discovered the drive shaft was missing and "someone saw the night instructor walking around with a drive shaft," but that is not unusual and it was decided that it was a shaft they always use for demonstrations. Later it was discovered that he had taken the shaft out of the F150 and he subsequently returned it. It just seemed like too much work to remove a two piece shaft for a demonstration, so I assumed it had a one piece. When I get the truck I will have to take a look and see what it has before deciding on what to change. Thanks for all the input everyone.

I was not saying it does not have a one piece shaft, I was commenting on the previous post. There are one piece shafts it is just that they are not nearly as common as two piece shafts. hawkrod

Kurt Combs · Post by **Kurt Combs** » Sat Feb 18, 2012 11:05 pm

It sure would be nice if it has a two piece. I am fine with replacing the front half of the shaft with the newer version and not having to take the tranny apart, that would be great. If I am back over on the college campus next week I will check out the shaft because now I am curious. Thanks for all your help Hawkrod.

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C-6 combinations, will 78 F-150 fit 72 F-250?

C-6 combinations, will 78 F-150 fit 72 F-250?

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Re: C-6 combinations, will 78 F-150 fit 72 F-250?

Re: C-6 combinations, will 78 F-150 fit 72 F-250?

Re: C-6 combinations, will 78 F-150 fit 72 F-250?

Re: C-6 combinations, will 78 F-150 fit 72 F-250?

Re: C-6 combinations, will 78 F-150 fit 72 F-250?

Re: C-6 combinations, will 78 F-150 fit 72 F-250?