th-350 vs. th-400

[Bain]

I'm needing info and/or oppinions on a tranny for my 81' z-28. This will be for street/strip but mainly strip, and will be powered by a highly modified n/a 350 i'm estimating between 5 to 6 hundred hp. So my question is this: which tranny would be most reliable to handle the power output asuming both were rebuilt with upgraded internals or would you recomend another that is better. If that is the case I would prefer something that would be a direct bolt on or one of minor fabrication. Thanks

[mazdatech177]

400 hands down. that was put in all the heavy duty applications. or you could go with the powerglide... that thing is a tank. only problem is its a 2 speed and would require some heavy mods probably. but id be equally concerned with your rear diff. for that kind of power id be looking at a custom unit if you havent already. something like a ford 9-inch

i think youll have trans mount and driveshaft mods to do no matter what you choose

[curtis73]

I would agree with that except the 400 takes the most power to run of any automatic. At the 500-600 level, a 350 can be built to handle it, plus save you some weight and friction. Could be worth a tenth.

But, I agree that the 400 is bulletproof. If you want a tranny that you can put in and forget, do the 400. If its an all-out strip vehicle build up a 350 and plan on rebuilding it every few seasons.

[Bain]

Thanks for the info. The rear diff. will be upgraded as well I just haven't made it that far back in the build yet. I have little knowledge of what to look for and how to choose the diff. however because this is my first complete rebuild and am studying the ins and outs racing aps. of each area (engine,tranny,suspention,driveline,ect.) one at a time.