CD upgrade for 1994 Cadillac SLS /w Bose

I want to upgrade the sound in a 1994 Cadillac SLS /w Delco Bose Gold sound system. I'd like to replace the speakers and the CD unit, I'm guessing the amp has to go too. I am considering the GM/Chrysler-Fit CD Players by Pioneer DEH-P77DH or DEH-P47DH, but the fit guide at Crutchfield says it won't fit, and I don't know where to look for a second opinion or a reason why, considering it was supposed to fit that general form factor. I found a few informative threads concerning this car in this forum, but not about that radio, and I'm still puzzled. Thanks.

That guide at crutchfield sucks, because they don't take into consideration that head unit adapters exist... But a pioneer head unit would be good, so would an alpine for that car ... of course there are a million types of head units out there but if you got your eye one pioneer that is all good. For speakers, JBL makes a good budget speaker and you can get a JBL amp to power it all. I don't know if you want subs, but for the whole system right now your prolly around $500 maximum (Head unit, Speakers, Amp). It really depends on your HU but you can basically steal it all on ebay. Competition = lower prices. If you want subs on the other hand, you might need a second amp or you could just get one monster 5 channel amp and you'd be fine. "I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.

The reason I was interested in that Pioneer unit is that the faceplate fills the entire area left by the factory unit. Alpine doesn't seem to have an equivalent, and I don't like those faceplates made to fill the gaps, they've always looked out of place to me.