I've recently bought an NTG 2.5 head unit for the W211. I still haven't received it yet but I have already decided to sell it as I don't want to have to do the conversion which requires a harness from the UK on a car I'm probably selling soon. I got the head unit for a price I couldn't refuse so I jumped on the deal.

I can do it for 850 USD shipped to anywhere in the US.