72 demon seatbelts?

I have a set of front seatbelts that I can't figure out? The first pair I believe is for the passenger side. It includes two of the harness loop ends that get bolted to the tunnel. One belt is about 20" long with the chrome male clip end on it. The other belt is about 12" long and has the female push button release. They are grained black with the rectangular square push button. The other set is I believe for the drivers side. It too, has the two harness ends that get bolted to the tunnel. It has one that is about 12" long with the female push button end. The other one appears to be about 60" long and has the push button end. Whats strange is that the two short belts have push button ends that look the same as the others, but they are bout 30% smaller and do not have any adjustability for length. The 60" one has the larger push button end and the belt is adjustable through the end. The two mentioned last with the 60" belt are labeled 3371 and 3471 and 9916 and 9917 with part numbers 3670789 and 3670793. The set mentioned first is labeled 3471 and 3571 and also 9916 and 9917 with part numbers 3670178 and 3670793. I am not sure what these are for. The car had no seats and I picked up the correct bench seat with center armrest. The two retractable belts were bolted into the car when I got it. I think I got these belts when I bought the used seat with the dropdown center. Someone thought these were for a bucket seat car and the PO was trying to put them in a bench seat? Does anyone here have any info on these belts or part numbers? I also do have the two roof mounted shoulder harnesses which were with the car when I bought it. So I think that they are original along with the two retractable units that get bolted to the inner rocker area. Thanks for all your advise.....