Hey all - I've relegated myself to the fact that, even though my project car is setup for a T5 manual, the cost to get the right replacement (T56) prevents me from doing so.

In the meantime, I've decided to drop in an auto, and go that route. I guess I was under the impression that a 700R4 is the best option (reliability, fuel milage, power to the wheels ability, etc). Is that true? I'm a noobie in the transmission department, so I need some input. What is the most desirable transmission for me to go with?

BTW - It will be mated to a 350 or 383 putting out close to 400ft/lbs. I will be doing some mild SCCA road racing, but it will also be my "fun" car.

I am one of the rare few that like the 700r4. I have had very good luck with it and make similar power to what you describe. More on the spray. I especially like the overdrive and lock up. Saves me money on fuel. The drawback to this trans over the other 2 is more stuff to go wrong. TV system especially. Adjustment must be perfect. Not a problem with factory stuff(setting up the tv), but on carb conversions it gets a little tricky. You cannot beat a turbo 400 for strength. Some guys are putting 800 horsepower through them in stock form with no issues.
The turbo 350 has a reputation for being strong as well. GM rates the 350 and 700 the same in the torque handling capability though. Some even say that they are super strong . I have seen them fail often as well. Depends on who you talk to and who you want to believe. The non overdrive boxes do have fewer pieces, therefore less to go wrong.
Weigh the options.
Only you can make the correct choice based on needs.

well i had an 82 s10 with a 355 and i was smoking 350 turbos all day long for two and a half years. 400 i couldnt kill it, 700r4 that damn tv cable is a pain

I'm putting a th400 in mine. Couldn't justify the cost to build a 700 that would still probably break under the power. It's a weekend bracket racer anyway and I only live 10 miles from the track

If your looking for something you can beat on and not worry grab a th350 or th400. Unless properly built to handle that kind of power a 700r4 isnt going to last very long at all. IMO their isnt a tranny in the world that is weaker than the th700r4 (other than chrystlers vans!), the things burn out behind a 150hp smogger!

I wouldnt even trust a built up th700r4 more than a few miles, try a few searches. I have seen numerous posts where people have burnt up their $2k 700r4's behind a moderately powered motor.


Ive got a junkyard th350C in my car after the 700r4 went south behind the original smogger 305, now its behind a somewhat healthy 350 and gets driven fairly hard and hasnt gave me a bit of trouble.