The current C300 (with a 228 hp 3.0L V6) comes with a 6M.
http://www.mbusa.com/mercedes/#/vehi...c=C&vmf=C300WZ
I haven't tried one; my issue with Mercedes vehicles is that, at least five or so years ago, their manuals were about the only ones I'd ever tried that left me yearning for an auto. Talk about terrible shift feel. I think that the new ones are better, but the C class has never appealed to me when compared to the comparable 3er.