CD Changer in ML 270

[ancuislean]

Hi, I wish to fit a CD Changer to a 2003 model ML 270 CDI, Internet sites say the wiring is there but you need to poke around to find it. I have searched the rear compartment and cannot locate either of the wires that are meant to be there. If they are this may mean removing the inner plastic side panelling, or maybe the 2003 model did not come prewired. I dont want to go to the trouble of removing this panel only to discover there is no wiring there. Any help would be appreciated. Thanks.