The silent cam chain drive was standard equipment on 1999-2006 Twin Cam, except 2006 Dyna. In 2006 the Dyna received the Roller Chain cam chain drive, which is also used in all 2007-2017 Twin Cam engines. There are also Hybrid Cam Drive Kits that use the "late" roller chain as primary cam drive and "early" silent chain on the cam-to-cam drive. Because of this we strongly recommend to check what is installed in your motor before you order. Replacement parts as indicated below fit the stock cam drive on Twin Cam 1999-2006, except 2006 Dyna. Unless differently indicated all parts are sold each. When you need more than one of an item this is indicated between parenthesis, for example (2).