my wagner master brake catalog only lists 11x2 1/2" rear drums as available on the charger. the only listing i could find for 11x3" rear drums were for chrysler new yorkers, newports, and imperials. this goes from 1963-1976. if there is indeed 11x3" brakes on your charger, i will have to say they were swapped on from a new yorker or a newport, as the imperial had a 5" bolt pattern. also, my 69 FSM only lists 11x2 1/2" rear drums even on police and heavy[taxi] duty brakes.