I'm looking for an automatic for my 90 bird. I'm gonna go with a manual valve body & ratchet shifter. I have a $150 3 spd shifter, but the 700r4's are easier to find and i think i might like a 4 spd better. I'm not looking to keep the tranny forever, but it's gotta be able to handle a 350 .30 over, and maybe some nitrous. Also, i've got 4.56 gears in the rear. Are the 3 spd's alot stronger than the 4's. I've searched this, but it's pretty devided on what tranny handles the best.

 

stock for stock the th350 is stronger than the 700R4 but either one can be built to easily handle your power.

The th350 isnt going to be a pleasant street driver with the gears you have in the rear.

Personally when i am ready to do a tranny swap i will be going back to a built up 700R4, Its got a lower first gear and the bonus of overdrive which will help my mileage because of the 4.11s in the rear.