What would be the best suited automatic tranny to pair with a mildly hopped up 350. With longevity and driveability as the preferred qualities. Also a the best gear ratio for fuel economy.

 

If I was going to stick with an auto in my car it'd probably get another 700r4. Its got a nice low first gear to get you out quick, and the overdrive is nice on the freeway. I wouldn't buy a stocker to put with a modded motor, but plenty of vendors out there offer stronger than stock examples at reasonable prices.

Best gear for mileage is the lowest numerical ratio you can find, like a 3.08, but realize that the lower (numerically) your gear, the more nuts it gonna cut off of your hopped up 350.

 

Well to be honest Im gonna put it in a Silverado, so... Would you still go with the 700R4 or would you go with something else. Can you think of any vendors off the top of your head that would produce such transmissions?

 

Yep, I'd still do a 700r4.

Back when I was thinking about doing the auto thing again, I found lots just by google'ing. I'd start another thread specifically asking about best deals on upgraded 700r4s. I found a few in the 600-700 dollar range without a converter.

That pickup is going to be heavvvvy. That and a 3.08 gear is really going slow that truck down. Call a Chevy dealer and ask what gear ratio a new silverado has, and try to get close to that. Thats about the best advice I can offer.