Hello,
Most part manuals list 82 to 87 parts being similar, but that could also include 1981. GM changed the body designation from A to G in 82, so they consider 81's different, but they're not.
There was a minor trim revision in 1984, so things like headlight bezels and tail lights are different (interior change too), but major body components didn't change. Bumpers, doors, ect, should be the same.