Starter ring gears often wear out as a result of "Hard to Start" High Performance engines. Ring gears are not available as a replacement part from "The Factory". As a supplier of High Performance engines we had these replacement starter ring gears manufactured. Saves you from replacing the entire clutch basket and ring gear assembly when you chipped a tooth from your starter ring. The required rivets or bolts are included. Gears are manufactured from top-grade materials. Ring gears are available in the stock replacement but also in a "Retro-Fit" style. The Retro fit style has 66 tooth and must be used with a special starter motor pinion gear ZPN 290546.