I took mine out to look at the part numbers and they are as follows:
bosch# 0261210171
MB# 003 153 27 28

Alldata shows # as 003 153 28 28
Mercedes dealer say new number is the same one Alldata shows.

Edited

I just put my CPS back in. I've read where people have trouble with the fastner falling out of the socket. Well I had no trouble, got it in on first try. I use a product called Quicksilver to hold the fastner in the socket. It's anti-corrsion grease and it's the stickiest stuff I've ever seen, I just put a tiny amount on one place on the fastner, if it was a liquid I'd say one drop. The stuff is non-conductive, nonelectrolytic, non-corrosive, and insoluble in both fresh and salt water.

It intended to be used on linkages and boat propeller nuts and the like. If you get it on your hands it's hard to get off.