Need Help-What are these bucket seats?

I am looking to order seat reupholstery kits. I need help identifying these bucket seats and back seat. They are currently mounted in a 74 Duster but I believe the car originally had as bench seat from the marks in the carpet. The previous owner did not know what they came out of either. The back seat folds down but the package tray is curved and it looks like something else is supposed to be there. Leaves an open curve that you can see into trunk area when the seat is up.
Does a fold down rear seat supposed to have a straight package tray that meets up with the back top edge of the seat when in the upright position?

Any help identifying the year of these front and back seats would be appreciated. Someone with a keen eye will be able to identify from the original upholstery patterns...I think 75-76 Duster/Dart Sport.
Thank you!