74 Scamp pain

Hi everyone, I have a 74 plymouth Scamp, 318, VIN VH23G4F210301, this thing needs new rear drums but......everyone list 9x2, 10x2 or 2.5 there is no listing for 11inch. Of course it is 4.25 bolt pattern with 2 13/16 center.I've checked the dimentions for Fury, Cuda, Challenger, ect but the outter dia. of the drum for them is 14 in, my drums are 13 5/8 outter, inner is 11 in. the braking surface is 2 1/2 in wide the total depth of the drum is 4 1/2 in... It may of had a dealer installed tow package because there are brackets welded to the rear rails. If ANYONE knows ANYTHING please HELP !!! Thanks CZ