87-89 rear seats are one style and 90-93 are another. The back half that folds down, i believe are all the same but the bottoms half of the seat ,clips in different, but that doesnt mean you cant buy all the hard ware to make them fit
87-89 are lap belts and 90-93 are shoulder belts.... so no they wont work either
As far as i know yes. Tell him send you pics of the under side of the seat and the floor board of where the seat clips to. Cuz if the seat was from an 87.... then it should not have worked in the 90 unless he swaped all the hard ware
You can get 90-93 quarter plastics to fit in a 87-89 if you drill a new hole for the front seat belt bolt. But you can not get a 87-89 plastics to fit in a 90-93, because of the rear shoulder seat belts that came in the 90-93.
To use the 87-89 rear seat in a 90-93, you would need to use the 87-89 rear seat mounts. The 90-93 uses a bar bolted to the floor while the 87-89 i think had a metal bracket welded to the floor.
To use the 87-89 1/4 panels in a 90-93, you will need to remove and fab new brackets (or use a donor) for the shoulder belts, and move the upper belt mount on the B pillar. And if you use the cargo shade, you will need a new one as the 90-93 i think was a bit shorter than the 87-89.