I have a 2004 Armada LE with Bose and 6 disc changer but it will not play MP3 CDs. I wonder if I can swap out my original 2004 radio/cd-changer for a 2006 unit to gain this MP3 playing capability (?) While looks may be deceiving the units do appear to be identical and in every way. One would think that the "MP3 feature" is implemented internally and should not be effected by anything outside of the radio itself. Does anyone have any experience with this?