TH400 trans?

[J-Ri]

Thinking about swapping a 350SBC into a '79 Cadillac DeVille that has a junk engine... mostly because I have that engine just sitting in my garage. The Cadillac has the TH400 trans in it, and a guy I know has a junk TH400 w/ Chevy bolt pattern trans he'll give me the bell housing off of. It's out of a mid-80s truck, we guess the bell housing should be all I need to get the SBC in there. Anyone know for sure if the bell housing will bolt to the slightly older trans? Car's not mine yet, so I can't just pull it and check.

Thanks-
-Jason

[silicon212]

The bellhousings are integral to the case on these units - you would have to swap cases with the two transmissions.

[J-Ri]

Originally Posted by silicon212

The bellhousings are integral to the case on these units - you would have to swap cases with the two transmissions.

Heh- of course, that's how this last month's been going!

OK, next question then. Should the cases be pretty similar (identical?) on the outside, except the bell housing bolts?

I've also got a bad transmission that was bolted to the engine I have. Pretty sure it's a THM350. I'll try to get a pic of it, but it's at the bottom of a pile of other car parts. The engine and trans are from a truck I bought for the 4.10 axles. Engine fired right up and sounded great, the transmission started slipping a few hundred miles ago so the guy put sawdust in it . I drove it a few feet and the trans gave up, so I pushed it home with my truck. It had a thick, gritty, black goo where the trans fluid should have been. Pretty sure it was a mix of gear oil and sawdust, perhaps with traces of the factory fill of Dexron II fluid. It was bad.

Anyway... If I have to swap internals on the 400, I'd just rebuild the bad one, I know absolutely nothing about the one in the car, no sense in messing with reusing the parts from it. It's also sat for almost 2 years now, I imagine it's got some rust in there. I've always heard the THM400 robs a lot more power than the THM350, but eventually I'd like to make 600 hp or so. For that, I'd rather have the THM400. I'm guessing it's not worth even trying to rebuild my THM350 as bad as the fluid was, I'm sure it will need every internal part, right? Sorry for the rambling on, I'm feeling a bit indecisive on this right now.

BTW, love your Jefferson quote!