old part number 000 821 09 63 has 3 prongs...ordered new one, I got 3.101.200 which has 4 prongs see

http://catalog.eautopartscatalog.com/mercedesshop/sophio/quote.jsp?header=header.jsp&footer=&product=0008210963&partner=mercedesshop&baseurl=http://catalog.peachparts.com/&clientid=catalog.mercedesshop&cookieid=1OZ0OB9FZ1QP15YXQC

will this part interchange with the old part?? I hate to install it, have it get fried or fry something else, and most places are picky about returning electrical items.

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Mark
1983 300TD Wagon
Even a broken watch is right twice a day