I want to put a 3.73 gear in it. It has a limite slip, and I believe the stock gear,2.75. It lugs around @ 1800 rpm @ 65 mph. It sucks out of the hole. I have a set of ported and polished, 1966 289 heads with big chevy valves, I traded for a C-4 tranny. They are O-ringed, comp springs, screw in studs, the works. I just don't know what rockers and pushrods to use. I am a technician for a GM dealership,but I like and have owned many Fords. Built a lot of early small blocks,but this is my first venture into Fuel Injection.