Most popular of our starter numbers is the Chevrolet TS400. It has proven itself to be the finest available to match up to a standard Chevrolet 168 tooth ring gear. However, recent developments in ring gear technology have led us to recommend a switch to a "ten pitch" gear form on the ring gear and starter. This deeper gear set is stronger and more forgiving. It nearly eliminates grinding of the pinion when it is trying to engage the ring gear because the ten pitch gear set has a larger opening for the pinion to get in to. If you already own a standard TS400 and would like to make the switch, this kit gives you all of the necessary internals and the correct noseblock to convert your starter to a TST400, ready to mate to a 139 tooth flexplate like our FPT300.