Th350 to th400 swap. What do I need?

[Project86]

Finally was able to pick up a transmission for the low low to get my project under its own power and work out any electrical bugs/chassis issues.

Previous combo was a sbc 357/th350 short tail and stock driveshaft

I'll be swapping in a th400. It's definitely a short tail and it's a HD trans as well

I know the governor will have to be swapped out since it was behind a diesel motor.

What all will I need for the swap over? It already has a yoke in the tail housing.

[PGSigns]

An off cross u-joint to go from 1350 to 1310. You may need to do some drive shaft work depending on what the lengths are of the two trannies you have. Will need to slide the trans crossmember back. You will need to set up a kickdown switch on the carb.
Jimmy

[Captainfab]

Does the TH400 have a bolt on yoke or a slip yoke? If it is a bolt on yoke, you will need a driveshaft with a slip yoke on it.

[Project86]

Originally Posted by Captainfab

Does the TH400 have a bolt on yoke or a slip yoke? If it is a bolt on yoke, you will need a driveshaft with a slip yoke on it.

Seems to be bolt on as it came out of a 3/4 ton diesel truck

[Project86]

So now what parts would I need to get rid of a bolt on yoke? I would prefer slip in as much as possible.

[Project86]

So some further research points me to a possible solution.

Dennys counterbored yoke.
Looked on his website and it says currently not available.
So my question is, what exactly does the counter bore do??

[Captainfab]

I don't remember the specifics but when changing from a bolt on yoke to a slip yoke a special yoke is required. There are a thread or two here about doing that. Is your truck a long bed or a short bed?

[Project86]

Truck is a short bed

I've seen lot about counterbore yokes. And I can't figure out exactly what that is

[Captainfab]

A short bed with a 1pc driveshaft? If so, check into what it would cost you to have a slip yoke added to the driveshaft at your local driveshaft shop. Then you just keep your bolt on yoke. That's what I have in my '66 Suburban with a TH400 and a bolt on yoke. That might be cheaper than the special slip yoke for the trans.

[Project86]

Originally Posted by Captainfab

A short bed with a 1pc driveshaft? If so, check into what it would cost you to have a slip yoke added to the driveshaft at your local driveshaft shop. Then you just keep your bolt on yoke. That's what I have in my '66 Suburban with a TH400 and a bolt on yoke. That might be cheaper than the special slip yoke for the trans.

Yeah it's an 86 c10 that used to have a 350/350.

I've got an aluminum head built 383 that's going in it, so I would rather eliminate the need for a slip joint within the driveshaft

[Captainfab]

A slip yoke in a driveshaft isn't going to be a weak point.