It could be your ball joints and/or other steering parts. I just replaced mine (lower) and tie rods and the clunk in mine ('91 300SE) is now gone. I am now a bit more picky as to who gets to touch my car, find someone who knows about a Benz. Center link will be replaced by me next week when my new starter comes in, then I'll be "on the road again......"

__________________
1991 300SE (my ride, 279,000 miles, looks almost new
1954 Cadillac (21 yo son's car, he bought when age 15)
1972 SeaBird 19 ft runabout (old but solid, slant six, Volvo sterndrive perfect condition, undergoing complete overhaul and refit)
1998 Toyota Rav4 (my sons daily driver when he is in the Continental US, PROUDLY serving in US Navy)