Is it really worth it? Is it a direct bolt in? where can I find some write ups?

I am gonna have to get my th350 rebuilt...$400 and was wondering if I would be better off putting that cash into making the th350-th400 swap instead.

Any and all opinions are wanted

Thanks, David

Why not go with a 700R4(?) or 200R(?)4 ? It has a lower 1st gear and overdrive!

Nope! Upgrades to a modern tranny nothwithstanding, the 350 is a better tranny than the 400. The timeline has proven that the 400 is overkill, and lots of people are running 500+ horse-lb/ft through 350's with no affect on lifespan of the tranny. I don't know the gear difference--if any between them--but the 350 weighs however many pounds less. (Enough to make a difference.) Also, the 350 has less rotational mass, freeing up additional hp/torque for the back wheels.

I agree with "Bronze Bird" - if you are going to swap, put in an OD tranny. I'd probably go with the 2004-R (even though I have a 700R-4!)

Cheers,
Scott

will a 200r4 or a 700r4 handle 500 hp? I wont be doing any drag racing but I will be doing alot of this:

http://s7.photobucket.com/albums/y254/gadjit/?action=view&current=MOV00940.flv

I wouldnt mind OD if I can get it relativley cheap and still have the durability of the th350.

Thanks,
David

You will not get much of an improvement with the 350TH to 400TH swap. I think the only advantage with the 400 is longevity. It would last longer than a 350. Simply because it has more plate wear potential. Having said that a 350 should stand up good to most street use. I have always wondered if a 350 trans verus a 400 trans has anything to do with the tendancy for a Pontiac to run hotter. Does a 400 trans need more cooling than a 350 trans? The answer is most likely yes.

Yes, the 400 generates a lot more heat than a 350. You don't often hear complaints of overheating on 4 speed cars where a similarly configured 400/TH400 may have issues.

I put a deep finned aluminum pan on my TH400, which helps bleed off heat on the highway. But when stuck in cruise traffic, no trans cooler will help much.

Gears are better spread in the 350. You'll lose a little torque multiplication with the 400. If you're going to swap go overdrive. The 2004r can handle 500hp when built properly but it's not cheap.

im not sure of this relating to pontiac transmissions but you can swap a chevy 400 trans into a 350 case and shed 20+ punds of aluminum doing it. the case does take the beating with no problems! that said you might check into doing the same with your pontiac transmission. also many here have converted to the 200r4 transmission but as stated in afore mentioned posts... IT AINT CHEAP! cost is around 2000$ for a fairly good transmission that will handle the power your plan on putting to it! id stick with the 350 or convert to manual if your worried about the fun factor!

Andy, I thought all TH400s had the same internals with minor exceptions. How do they get the innards to fit into a TH350 case?

they are indeed one and the same. its only a matter of removing a small amount of material toward the rear of the case. cant explain where but i do know where to clearance it. you might check out camaro performers mag to get exact details on this as they have done this mod befor for a tech segment.