Have a pair of what seem to be A body 2 piece disc brake rotors. Same dimensions and such, but the bolt pattern is 4.5" with 1/2 studs. Has the smaller A6 inner bearing and the studs cross to a one year 72 Chrysler type by a Dorman catalog.

I have been told some super stock A Bodies had the big bolt pattern disc brakes, but that the 340 A bodies did not get it until 73. I also thought by 73 all rotors where one piece, but no expert on this. Any idea what they came from? Did some late 340 A bodies get the 4.5" bolt pattern with disc brake option?