There will be a number on the body of the starter. Use that number to look up the starter on the "old chevy manuals' site. If your starter is 6 volt, you probably need to replace the drive. If the drive is worn and loose, it will cause grinding that destroys the teeth on bothe the drive and the ring gear.
From reading past posts, flipping the ring gear requires a little machine work to allow it to fit on the flywheel upside down.
