Hello evereyone! I just recently purchased a 2005 ML350. The dealship I purchased from said I could take it to the Mercedes dealership to have the navigation installed since it was already pre-wired. Where can I find an unit for this model? I would like to avoid the cost of the mercedes dealer and install it myself. When i press the navigation button it says NAVIGATION IS NOT INSTALL, same thing on the phone button. Do i have to buy another device or just the CD to get this thing working? I have cd changer in the back but i can't play any DVD. And also i noticed my LCD screen looks like black and white when i play music CD. Any ideas?