I have a '68 GMC truck with a Turbo 400 in it now and have a nicely warmed up Turbo 350 tranny given to me, that's right for 0 dollars, but the tailshafts are different...question is are the tailshafts interchangable from the 400 to the 350??? Looks like the difference is about 3" but I'm not sure if the tailshaft will just come out of the 400 and slide right into the 350, as you can tell I've not had any experience with auto trannies...any help would be greatly appreciated...email me if you can...

Thanks in advance,

Shawn

 

No. They are not interchangeable. The TH400 has a large diameter output shaft while every other GM automatic has a smaller output shaft. There are also other differences.

If tranny swaps were that easy, people would have been suggesting swapping tailshaft housings years ago.

 

Thanks IROC it didn't look like it would be that easy to me also, o well I'll just have to sell this one and have mine rebuild then

Good to have these forums to make sure if we're not sure and have someone with the knowledge to step and give the rest of us the direction we need.

Thanks again!

Lower68GMC