Years a go I had a 64-1/2 Mustang, and my recollection is that all the numbers for that particular car started with C4ZZ and then a part number. Then, years later I got the Model A and it didn't take me long to realize that the parts all had a very distinct similarity to them. It would not surprise me if some obscure part designed for the Model A was still being used in the 64 Mustang. However, as a 20-something year old and broke, I used to frequent junk yards to buy my Mustang parts in the '70's. It occurred to me rather early on that I would pay a lot less for a part to a 170 cu in engine if I asked for the part for a 64 Falcon rather than for a Mustang.
