Sorry, I think the NOS numbers should be C70A.
C7OZ are the repro numbers
Ford part numbers with a letter in the fourth position, the "A" in C7OA (and it is the letter "O", not a "0", zero, in the third position) indicated the engineering department responsibility, in this case, "A" indicates "Body engineering. The letter "Z" indicates that the item is now the responsibility of Ford service ("Y" is Mercury service). NOS means "New Old Stock", an acronym for service parts. Many vendors/sellers of aftermarket items use the Ford number to identify their parts, and you are correct in that many aftermarket parts are not really that good.
The letter "O" in the third position indicated that the item was originally designed for Fairlanes/Torinos. A Mustang designed item will have a "Z" in the third position. This leads to some confusion as a service part number for a Mustang will have "ZZ" (double "Z's") in the third and fourth position.
Confused? It's a learning process.
Jim
