will a th400 from a older corvette work with a71 olds455 motor a have a th350 in it now the car is a 67 cutlass convt

 

You can make it work with an adapter, the bellhousing is a different pattern. It also may be a short tail shaft trans and I think the yoke is different between the TH350 and the TH400. Someone else probably knows more than I do and should chime in soon.

 

The 400 spline shaft is thicker than the 350 shaft, so you will need a different yoke is swapping between the 2 different trannies.

The 400 also came in 3 differnet tail housings. 4 inch, 9 inch and 12 or 13 inch (don't remember exactly) Also the speedo gears are inside the tranny housing, not the tail housing like the 350.

Yes adapter plates work well, but it sucks for us Olds guys. A BOP tranny to a Chevy plate is around $50, but a Chevy tranny to a BOP engine is closer to $100

 

I've used the BOP to Chevy plate behind a BB without incident.
Seems silly to have 2 prices as the difference is a couple of tapped holes!

 

http://www.afabmetalworks.net/Fabricated%20Parts.html

 

I agree