A 3.90 rear with a 3-speed will have your motor screaming at highway speeds. Go with either a 5-speed (if you want a gear ratio in that range), or a 3.08, 3.23, or 3.42 and a 3 or 4 speed.


1946 GMC Pickup - S-10 Frame, 455 Buick, TH400, original patina.

My 46 GMC on Photobucket