I recently purchased a boat with a 1972 Evinrude outboard on it. As the mechanic was helping me to get it started, the key on the flywheel broke yesterday. The groove where the keyway goes in on the flywheel is "wallowed" out. I was trying to obtain another flywheel, but from what I've read that flywheel is no longer available. The part # is 0581006. Is there another year model that will interchange with this year model? Any help would be appreciated. This is a 100hp motor