Hi,

Those parts are available on this site from the All Parts Express link. This should be the one:

http://www.allpartsexpress.com/ShopByVehicle.epc?q=1998-MERCEDES--BENZ-C--80--/--V6--799cc--.8l--Gas--Fi-Engine&yearid=1998%40%401998&makeid=MERCEDES+BENZ%40%40MERCEDES+BENZ%40%40X&engineid=1316353%40%40C280++%2F+V6%2D2799cc+2%2E8L+GAS+FI%40%40C280&catid=Engine%40%40Engine&subcatid=Belt+Tensioner@@Belt+Tensioner&mode=PA

There are 2 parts involved. There is the tensioner assembly and there is the pulley. I am not sure what you mean but you need to see where the looseness is. That link above is for the whole assembly. They have a nice photo you can zoom in. You can also buy just the pulley part for about 20.00.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra