I haven't got a clue if Kelsey Hayes ever produced a rotor-hub assembly, back in 1972, with a 4 1/2" inch bolt pattern, for an A body automobile.
It certainly wouldn't have been for any regular, assembly line, production, automobiles.
Running off a batch of them, as replacement parts, for a 68 Superstocker, who knows.
I doubt if anyone knows.
I used to rebuild these Kelsey Hayes a body disc brake systems for resale purposes, and i kept track of all the ones that i rebuilt during the 12, 13 years that i was doing them.
Rebuilt 32 sets of brakes in that time frame, and never came across anything with 4 1/2" inch bolt pattern, for a Mopar A body automobile.
If you do have a 68 Superstock pair, they certainly would be dinosaur eggs, hens teeth, unobtanium parts, to have in this day and age.
But a very, very, limited market for them if the rotors aren't machined undersize already.
For street A body cars, the enthusiasts are just buying the one piece Mustang rotors for 4 1/2" bolt pattern machined for a Mopar, that a machinist, vendor, advertises on the web sites.