Correct belt is dependent on engine serial number. Check this link for production breaks
http://catalog.peachparts.com/ShopByVehicle.epc?q=&yearid=1994%40%401994&makeid=63%40%40MERCEDES+BENZ%40%40X&modelid=6391%3ABT%7C5%3AMBC%7C1508%3AED%7C10000022%40%40E320+Sedan&keyword=belt&subcatid=P:242348@@Multi+Rib+Belt&mode=PA
Early production 104.992 had belt tensioner with adjusting barrel, late production 104.992 had different style tensioner. That's the reason for different belt lengths. Autozone and other mcparts outlets have incorrect information on their database.
If your engine calls for the 2415 belt (old style tensioner) a 2375 (Gates 935K6) will work with smog pump removed. I currently am running this belt on my 94 wagon while I wait on smog pump rebuild parts. If anything, this belt is very slightly to loose, if I were at the parts store again, I'd try the next shorter.......
If you have the later style tensioner, I would try a belt that is 0040 or 0045shorter than stock.
Hope this helps.
J. M. van Swaay