Which of these two is better. I am getting ready to put in a new transmission but my uncle told me that I should keep the 700r4. He said it is the best transmission GM has ever made.

 

the th 350 a alot stronger in a sense that is will take alot more abuse but it doesnt have over drive like the 700r4 does.....
the 700r4 is a good tranny but if you are going to have an engine that is making any real power and you dont realy care much about gas milage id go with the th 350 but if you are going with a mild engine and drive the car a good amount id go with the 700r4.... through a corvette servo and govener in it and it will be a fun tranny for you..... but if you are going with an engine that makes alot of power and you still want over drive you can have a 700r4 built to take the power and have the advantage of over drive.

 

Not to highjack, but what kind of shift kits are people putting into the 700?
BTW, I have both trannies and the 700 seems a little more responsive and definitely has the advantage of o.d.
THM 350 is fine, now, I've heard some awesome things about the 400....

 

The 700 has a lower first gear ratio, a 3.08 I believe. Thats probably why you think it is more "responsive" As far as it being better, I dont think so. Some people do, some dont. To make a 700r4 as strong as a decently built 350, will cost about 2-3X as much. IMO its not worth it, cause I dont need the overdrive. The 400 is a little stonger than the 350, but it has a worse first gear, its more of a truck transmission, IMO. Lots of cars had them though, and they are a good trans to use in performance builds. Its just that a th350 will handle just about anything you can throw at it, when built right. Now, cue someone to come in and say "the 700r4 is just as good, it can be built just as good". It can be if you feel like spending 3x as much.

 

I wouldn't go that far.

I wouldn't want a car if it didn't have overdrive. My 83 SS will get something different (has TH350-C) at some point.

The thing about transmssions is you can't crucify all 700-R4's as being "junk" just because of a few that had trouble. I know someone in Albuquerque who will be happy to warranty his 700-R4s behind 454s and another guy in NM who will warranty his 200-4Rs behind 454s.

If mileage matters at all, the 700-R4 is the better choice. You just need the right shoppe to build it and the TV cable adjusted right and it'll be the better trans., because not much takes precedence over OD.

 

When mileage is the prime concern, this is true. You will never come close to the mileage of a 700R4 w/ a th350.

 

You can only compare apples to apples.
I thought we were talking about "out of the box" characteristics, that's where my comments apply...

 

It all really depends, if you plan really going hard, and going with a drag car, chances are a TH350 is probably for you...

but for street racing, and that sortof thing, the 700R4 is a better tranny with more room for improvements.

 

So just what is "a mild engine" that a 700r4 can handle? An L98 bottom end, ported L98 heads, Performer intake, Lt4 Hot cam, and a 3" exhaust? Can a 700r4 handle that for 10k miles?

 

it'd take it, yeah.
dont be confused, its not weak, its just not as strong as the th350

 

If it can't, then a part failed, or someone didn't build it right. Stuff happens, but that should be no challenge for a good 700-R4.