This exhaust bushing is an aftermarket replacement of OE number M13-1011, is made of polyurethane & is sold individually. The exhaust bushing fits Kenworth T600 Aerocab 1993 thru 2007, Kenworth T800 Curved Glass 1994 thru Current, Kenworth W900B Aerocab 1994 thru Current & Kenworth W900L Aerocab 1994 thru Current trucks.