LBP vs SBP 8.75 Brake Backing Plates

Had a friend bring over 3 sets of 8.75 brake backing plates. He said he thought 2 sets were from an A Body 8.75 and 1 from a B Body but could be the other way around as he didn't mark what came from what when he removed them long ago. What's the easier way to tell/show him which ones fit what?