Call 1(800) 222-0100 [Mercedes Customer Service] , give them your VIN#
and they will tell you the originating dealer, who may have the info.

alternatively, look at your "Freeze Plugs" one of them will either have a two
pronged male plug with lock or a cord with a male plug on it's end somewhere
on the front side of your condenser/radiator.

Good Luck!