Bose CD receiver for 89 vette

[SkipI]

I saw a while ago on ebay, a CD receiver for an 89 corvette that was Bose and a direct fit. Yesterday, my Mid-America catalog comes with a Bose CD unit that will direct fit 84-89 vettes. The problem... $550.00 is WAY too much. What radios are these? I thought I remember something about cadillac radios, but do not remember the years. I'd like to start searching on ebay for one of these for less $$$$. I recently had all the bose speaker/amp units rebuilt by bose and would like to get a compatable bose head unit. Thanks, Skip