If you can't find a wagon back seat, a 64-66 Barracuda is pretty much a bolt-in if you have all the seat parts. The only real mod is welding the brackets that secure the seat back locking rod.
I need a driveshaft for a 66 Valiant (66 Dart stationwagon) and a good, working slant 6 auto radiator for the same. The closer to central Florida, the better. Oh, I also need a back seat for the station wagon.