The ‘74 drum/drum cars all got the redesigned 10” front brakes, but the 9” rear drums were continued. So a ‘74 drum/drum car could have had 10” drums in the front and 9” drums in the back. All in the factory TSB…
Sorry I was late to the game! My ‘74 was a disk/drum car with a 7.25 and 10” BBP rear drums. I swapped in a 68-70 B body 8 3/4, used 11x2.5” rear drums, and yes, the stock parking brake cables. All the same!