Been lurking for a while now trying to learn what I can.
How do I know if there is a factory installed block heater.
1996 E300. I called a nearby dealer who didn't seem to know much. He quoted $138 for a heater.

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!

I suspect the location is the same on your newer 606.

http://www.peachparts.com/shopforum/showthread.php?t=76493&highlight=block+heater

Rgds,
Chris W.