In all the reading I've done over the years, it not much other than what you see. The wheels were reduced to 18" because of costs to stay with 19" tires in production. Exhaust the same reason. Although alot of people thought the tuned system that we got that uses exhaust pulse technology was actually a better move. I read in GM Insider long ago that the ShortStar was kicked around before using the LD8. And happy of that. I dont see enough difference in the wheels to mention other than size. Would have been great to have had them in chrome. All in all, with so many concept cars that never make it into production, and those than make drastic chances from the prototype that do, I don't see most of the negative criticisms between the two as valid. Just the usual "some people are going to complain for the sake of it." My only real big peeve is them using the locked PCM. But I can understand the warranty issues being the tight parameters the engine is designed to run under. If I was the manufacturer, not the end user.