<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by 501:
Can anyone tell me if the 6-disc changer can play MP3 CD's also? </div></BLOCKQUOTE>

Thats a negative. There is an optional $700 single disk cd/mp3 deck you can order from the factory, but you would be better off spending the money on a good aftermarket deck.

Will changing out the factory stereo affect other functions, such as Onstar, door/warning chimes, etc....? That is the reason I never switched out my factory 6-disc changer in my Avalanche, because I would lose everything else.

It depends on what you're putting in it's place. If you are putting another OEM H3 radio, then no, it wont affect anything. If you installing an aftermarket radio, then you need to check with the installer to make sure that they install it properly so you don't lose those functions. i think there is an adapter or something that can be intsalled to integrate it into the radio.