The only other things I can think of that the '90 has that the '87 doesn't have, are rear seat shoulder belts, and map pockets on the door panels.
BTW (useless trivia), did you know that during the production run of the '89 Mustang, from 8/31/88 through 9/5/89, the factory at Dearborn cranked out 46 new Mustangs an hour, every hour?
That's a lot of parts cars, gentlemen.
