My 1999 ML430 came equipped with the Bose single din head unit with the remote CD Changer in the back.

I looking at installing an OEM Nav System. My problem is, there are numerous parts numbers for what appear to be
the same MCS unit. One parts guy I spoke with said the only thing that will work would be Part #163-820-04-86 or
#163-820-21-86. Others say BS -

What parts are compatible and what do I need in the way of Nav Drive units.

Is it even worth it? There seem to alot of aftermarket units that have more updated features -

 

-21 is a later version than -04, the A163 unit is the easiest to fit as its for the ML just need a harness adapter and a sat nav antenna but it is possible to fit A210 and A208 units but these require more than a simple harness adapter as they are for other models that have CAMBUS and this needs a special adapter make the unit work.