I agree with Hotrod. These engines came from simple times. Most were repaired either independent mechanics or the owner under a shade tree. Very few mechanics had ever seen a shop manual. There were no reprints around and no eBay where many are sold that look almost new. They survived 50 years because dealerships were required to have them, but no one ever looked at them. Just break the old gear off and put on an aluminum one. Aluminum expands a lot when heated.
