I have a 2001 ML320 without a navigation system. I found a DVD unit on ebay for a 2002 model. Apparently the 01 models ran off of CDs while the newer models run off of a DVD. Does anyone know if it is an easy install to put an 02 unit in an 01 vehicle? Aside from the basic unit that fits into the dash, are there other major parts that I would need to make this work?

I appreciate any help anyone can give me.