Early Discs? Not mine on CL

You can use 73 and up rotors on the 70-72 B&E body spindles by using the bearing adapter that DR. Diff sells. Jim is right, in that the 2 piece rotors for the 70 - 72 spindles cost out the ying yang. They also have a tendency to warp to hell and back. When I get around to fixing my 70 Challenger 340 that I have owned since 1979, I will be using later rotors with the rear bearing adapter. Front (outside) bearing is the same for both types of rotors.