Hi All!
Need some help deciding on a transmission. I have a 1980 with a GM ZZ4 engine and Dynoed at about 451 Hp. My question is this....Should I Keep My TH 350 (which has been hopped up a bit) or go for something like a 200r4? I want the power and don't really
go THAT much racing....although that feeling sometimes creeps up when I am next to a Hemi Charger or the like..... and would like to have a little better Gas Mileage than I do now.....anyway.....thoughts on the 4 speed autos?

 

Hey Y'all..
I recently had the same decision to make. With a little help from people on the forum, I'm goin' with a 400 HP, 454, this backed by a 3sp. w/OD, that came out of a '56 Chev. HT. (that I just happened to have "layin' around", for 30 yrs.)The rear is a 3.07:1.

Since you have the 350, and it's built somewhat, go with that.

 

I don't know what mileage you are getting now but I will tell you I have a similar setup in my 69 camaro.
I get 5-7mph on the highway.
If I changed the rear or put in a trans with overdrive the mileage would go way up.
Down side with rear change the car would be a dog off the line.
Best way to go is trans with over drive.
Good luck.