I am also looking for a special tool. I have a '88 300SE and I would like to clean or replace my fuel gauge sending unit. I want to say off the top of my head that the size of the socket need is 27mm. Any one has one they want to sale? I will try the sites that you mentioned eariler I noticed that one thread I read said that it would be 1 13/32 or the 27mm I think.. any suggestions?