2005 Armada mp3's?

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?

UPDATE: It always bothered me that my 6 disc player in my 2004 Armada with Bose, Nav, etc. would not play MP3 CDs. I bought a 2006 CD player on Ebay for $84 and it arrived earlier today. I swapped it out with my original one (it took 5 minutes) and now I have MP3 capabilities! I know this may still seem old-school by today's standards but as I mentioned a couple of posts ago it is virtually impossible to upgrade the head unit in my "fancy" LE version of the Armada due to the car-computer, nav screen, climate control, etc. and still retain all of this stuff on the nav monitor. This was an acceptable compromise. I have also added the Naviks unit for backup camera viewing on the nav monitor and mirroring of my Android phone.