[JC455]

What do I have- it appears to be a BOP TH-400, but the output yoke is bolted in... what gives?
Can a regular slip yoke be used?

[242177P]

403 Olds, but yes, you can use a slip yoke. There are some specifics that elude me, but the one you need doesn't have splines running the entire length (because the truck output shaft uses an o-ring)

OPH knows, I'm pretty sure it was his posts I gleaned that info from

[Half-Inch Stud]

Truck TH400. Yes you can remove the bolt & Yoke then use a sealed slippy Yoke.

[JC455]

Ok, thanks for the info... By sealed, you are referring to a standard TH-400 yoke, yes?

[dataway]

I'm curious ... what was the reason for having it bolt on? I assume there was some sort of sliding shaft downstream?

[JC455]

I guess it's a "truck" model- maybe a GMC product w/ an Olds 403- that GM decided to bolt the yoke in place and have a slip section in the driveshaft...

[242177P]

Originally Posted by dataway

I'm curious ... what was the reason for having it bolt on? I assume there was some sort of sliding shaft downstream?

Yep. A 70s crew cab needed almost nine(!) feet worth of driveshaft. So they used two driveshafts, with a crossmember mounted steady bearing and a slip yoke in the middle. Well, closer to the front, but you get the idea...

[stevep]

It may have been form a late 1970's diesel truck

[taff2]

Jaguar TH400's had a bolt in yoke with round flange.

[Schurkey]

Originally Posted by 242177P

403 Olds, but yes, you can use a slip yoke. There are some specifics that elude me,

Me, too.

Originally Posted by 242177P

but the one you need doesn't have splines running the entire length (because the truck output shaft uses an o-ring)

OPH knows, I'm pretty sure it was his posts I gleaned that info from

If you use the O-ring seal on the output shaft having an O-ring groove, you need a vented yoke or the yoke will create vacuum as it pulls out of the trans and bind-up.

If you don't use the O-ring, the vented yoke will piddle trans fluid. Gotta have a sealed yoke, and an output shaft with a missing spline. The missing spline becomes the vent for the yoke, but it vents internal to the trans, so no fluid loss.

So I think those are your two choices: Either you have an O-ring on the output shaft and a vented yoke; or you have a missing spline on the output shaft, and a non-vented yoke.

I don't know how the bolted-yoke output shaft is set up.

[Cliff R]

I've got a couple of TH400's here in the shop with a bolt on yoke. The are Chevy truck cores. I've seen a few others over the years but can't remember if any were BOP, I was thinking all the ones with a bolt on yoke I've done had Chevy cases.........Cliff

[ErikW]

Probably Olds diesel in a GMC like stated earlier. I always put the shaft in a lathe and cut down the o-ring bulkhead so a regular yoke works.