Like Plakt says. If you get the rear end or center section from a 67-72 3/4 ton truck with v-8 & auto trans. It is a bolt in swap. Most of those had 4:11 gears. They are pretty rare though.
George
Not most, i believe all came with 4.11 with that specific drive option. Im sure the post police will confirm or deny the specific info. I got mine from a 72 c20 suburban with that exact setup
