I have a number of new Mercedes ML Series Trip Computers A163 540 52 11 and have sold a number of them on ebay with instructions on how to install it yourself in any ML that didn't come from the factory although they can also replace any defective unit that did come with the car too. It requires cutting a square hole for the LCD display which would not be required if the fascia panel was available from Mercedes, but as of yet I have not had any luck on getting a part number for the fascia panel. to view a tour of the functions of the overhead onboard computer go to this link
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you would like a 580 kb email with adobe instructions on how to installthe unit please feel free to email me at snipped-for-privacy@kc.rr.com I have located the part number for the remote compass module #163-545-57-32it list for 44.10 from the dealershipThanks!