ddgonzal wrote:
1975-1982 all use the H150 differential -- you can swap the center sections (pumpkin) to get different ratios.

1971-1974 used the H145, but they say you can swap the H150 pumpkin into them anyways. Theoretically you are supposed to use a 2mm shim where the gasket goes.

Details: club wiki, search for Differential