I am not sure exactly what rear end you have but its probably an eaton HO 33 which has a gear ratio of 3.90:1 I have a 56 1/2 or 3100 with a 235 an what I am planning on doing is rebuilding the 235 motor keeping the original 4 spd which is a SM 420 transmission. I also have 3.90:1 eaton HO33 rear end. I know of a company in Casa Grande, AZ called Patrick's that have a kit that will fit into your rear end with 3.38:1 gears which will get you speeds on freeway of 70MPH. Thats what I will do to mine. Ifyou are looking to put a auto transmission OD will help you. There is another company called Advanced Adapters Inc. that was going to supply me with an adapter if i ever decided to put a v-8 in mine Hope that helps. call Patricks they can help he help me decide on what to do.

"As I lay rubber down the street, I pray for traction I can keep, but if I spin and begin to slide, please dear God protect my sweet ride." -Amen

56 Chevy 3100