Definately change the belt with one of known quality. Also it is easier to check your distributor cap, rotor, belt tensioner and tensioner shock. The idea is to keep you Benz on the road.

__________________
1990 190E 2.6
1996 Grand Voyager 3.3
1985 Mustang GT 5.0 5 SPD
1982 Suzuki GS 750T