Are rear seats interchangable on all A-bodies?

TMI has a rear seat option for a 70-76 duster. After reading the thread, it seems that this option would not fit my 69 dart 2 door swinger, correct? I'm looking at getting the TMI sport-x pro-classic buckets up front and wanted to match the rear. I bought a rear bench from an old 74 dart sport that fit right in, but I have no idea if it was a 2 or 4 door, neither did the previous owner.