The Chrysler Imperials came with the 9 1/4 rear, as well as 4W ABS Disc. I know it was available in '71 but not sure what years it ran through, or if it would be much of an upgrade. Imperial wasn't a lightweight though.ddart said:i would look into a disc brake conversion for your rear. iassume you have the 9 1/4 im sure someone makes a kit.