[Jeff Lee]

The logic used by Rod is sound BUT I think all these new factory hot rods are all one part number approved at a time; i.e., the Ford 9" used is specific to the 2012 COPO and any subsequent COPO's ONLY.

In the case of my AMX, Chrysler bought AMC in whole in 1987. The Dana 60 was a regular passenger car production item for Mopar vehicles so once AMC was a Mopar vehicle, the corporate rear ends were allowed.