"@Ray Nice 36, and great article on your rear end gear swap. Im thinking of changing mine to the 3:38. I have a 57 3100 w/ 265 and hydramatic (doing the swap) and I don't thing I won't like how it drives with the 3:90 at higher speed"
Good morning Cozsum,
I don't think you would ever regret having a rear gear ratio numerically lower than that 3.90. One option you have that would allow retention of the 3.90 is an overdrive automatic. I took a TH350 out of my roadster and put in a 200 4R and with 3.80 rear gears it's humming at a fast idle at highway speed in OD (0.67:1 ratio).
My son is doing resto mod on a '66 Chevy 1/2 ton and I found him a rare 3.08 ring and pinion for it that he will be using with his TH 350.
Good luck in whatever you decide. Please post a photo when you get a chance.
Ray W
Last edited by yar; 05/26/2020 3:22 PM.
