I'm helping a friend with his Caddy witha 472 engine 125k miles, the transmission has failed. Neither of us are sure what type of tranny is in it, but I believe it's a TH400 . question: would a th400 from a 73 pontiac bonneville bolt up? the bonneville has a pontiac 455 engine. I'm not sure they match up. thanks th

They should be identacle unless somebody changed something. Just verify that the oil pan is shaped like Texas, the vacuum modulator is on the side and the tailshaft housing is the same lengh; should be long tailshaft. It's very hard to kill a th400. I have never done it and I still have every th400 I ever owned. Somebody must have hauled a big trailer with that Caddy.

I think only the caddy has the long tailshaft... the whole transmission must be taken apart to change the tail....look for a transmission from a 68 to 76 RWD caddy....

Describe the failure. Wont move, slips, leaks wont upshift from 1st??

Why not just have it rebuilt?

That was my suggestion, but for some reason he just want to change the unit out. probably because it's cheaper. He has found a THM 375. it looks the same but we have yet to install it.

What happened to the Buick Trans? The 375 will need a different yoke.

Well, What Happened?