Rear seat interchange

Hi everyone. I've got a '69 Barracuda notch and I'm finishing the interior restoration. At some point in the past, a lot of the interior was replaced with stuff from a '72 Duster (center console, 3 out of 4 door panels, and the rear seat). We only noticed the rear seat was wrong because my upholsterer was having too much trouble trying to stretch the upholstery over the rear seat frame, of course after they've been blasted and powdercoated to look brand new.

I'm surprised the duster seats fit as well as they did, so my question is - what, if any, years/models have rear seat frames that match the ones that should be in my '69 Barracuda notch? Are they all unique? Are the tops interchangeable but the bottoms different perhaps?

Photo of the rear seat when I first got the car. 67584235_10157641899655854_106303451348074496_o.jpg