Common points are at the front of the engine where the timing chain cover meets the head. It's kind of "c" shaped.
The other common place is at the right rear corner (and I do mean corner) of the head (passenger side).
2001 E430, Bourdeaux Red, Oyster interior.
1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".