Look agian, its buried a little but its there
here is the socker im talkin about.
http://www.samstagsales.com/mercedes.htm
its M0035a
Ive compared the diesel and gas inlet filters and they are same size. Even though the description says gas tank.
I think craftsmen or snap sells a 46 mm socket but I dk it will fit. I've always used a pipe wrench to remove the inlet filter.