Some one correct me if I'm wrong but you'll nee a lot more than just the radio unit. The wiring harness is diffrent along with the amp and the system also has sub-woofer.

One thing that I an not sure about is how you watch the dvd in the ML, so maybe some one that has the option can chime is as to where excatly you load the dvd.

 

I am quite sure you are correct, ML systems are quite a bit more than just a head unit, if you really want one, I would advise trading in your car for one that has it stock.

 

If you have the ML system and insert a DVD into the cd player, it will play the sound and video thru the speakers/nav screen as long as you are are sitting still. As soon as you start driving, the video will stop and sound will continue. To view while moving, you will need to do something else to modify the system. Someone else can tell you how to do that.