Unless you've got your heals dug in and absolutely want an OE 71 pop open gas cap, I would look at one of the new repo caps. The D2ZA-9A112-BA is actually a engineering number and indicates that engineering had released the part for 72 production. Ford was taking some heat from the Government over the caps design. During some accidents and roll overs the cap was not sealing as well as the twist on caps and in some instances was "Popping" open and spilling fuel. The new cap is sold by all the major Mustang parts suppliers, including CJ Pony Parts and Ohio Mustang Supply (on site vendors). It has the outer appearance of the original cap but has an inner twist on cap that seals to the filler pipe. Some sites may sell it by the original part number D1ZZ-9030-C.