I installed the w124/om603 version of this part on my car a year ago when the old on started leaking. Still holds pressure without issue. It was a pain to install. Be prepared to pull the clutch fan and radiator.
http://www.********.com/catalog/x,carcode,1194083,parttype,916
In the above URL you'll have to replace ******** with ROCK AUTO. Pelican doesn't carry the part.