back bench from 73 swinger in 71 scamp?
My two cents from the 'cheap seats' is 67 to 76 2 door Darts were the same size. Scamps would also be in the same catagory as 71 to 76 is in fact just a Dart with Duster nose treatment as anyone knows. I do know that Duster or Demon/Dart Sport rear seats are different but only in the height of the rear seat back as they are about 4 inches taller due to the style of the car. In addition 4 door Dart, and Valiant use the same size seat back but the seat bottom is different. having said that 73 was the start of the large retractors in the rear seat belts so the seat will have a taper toward the back on each side to allow the retractor. Other than that they should be the same size. Only thing is I am not sure about the hangers on the top of the back seat in the 73 being in the same place as they are in the 71. One quick way to figure that out is look at year one, paddock, or legendary for the divider panel sold for behind the rear seat back. If it is listed for 67 to 76 the seat back hooks should be the same as there is cutaways on each side of this panel to allow the piece to fit meaning they are all in the same place. Good Luck!!
Chas.