Also if you are concerned with originality be sure and ask the Mustang parts store if it is an Eaton or Thompson style with larger filler tube (straight=non ac and bent for ac). Mustang's Plus will try and sell you a non-original standard replacement for $120.00 which is the same one you can pick up a Kragen, Autozone, etc.
EBay does list original (Eaton and Thompson style) replacement rebulit pumps from time to time.