One of the things I don't like on the later ones is the rear seat belt bolts, for top removal. Can't recall the year split, probably about '88 on that, my '87 doesn't have the ones bolted to the top. Not a big issue, but IMO the '87-91's otherwise are the best there are. (of course, full removable top and emissions exemption in some locales is important)
241 t-case '89+, '88+ better trans (although likely already rebuilt regardless of year lol), '90-91 electronic speedometers, both seats fold/slide forward for '85 (some) and all after, radio dash cutout in about '88 or so is made for modern radios...and probably a few other things I've forgotten. Injection of course is the major difference in driveability.