Since you'll be in there consider getting the smaller diameter double pulley used on the OM617 300SD after they stopped production of the W123. You would use 1000mm belts instead of 1035mm belts. Everything turns a little faster to benefit all components in stop-go traffic and at idle. It's especially helpful with the water pump and the compressor if you run a/c. If no a/c and no engine temp issues it might not be worth chasing.