I've a 1983 R80RT and I have to pull the final drive for a thread repair. The four nuts holding the final drive to the driveshaft appear to be made to accept a twelve-point socket. A 12mm twelve-point socket seems to fit pretty well. Or is there a special type of socket made specifically for that type of nut? My Clymer manual doesn't address this. Also, what's the best type of thread repair system to fix the driveshaft fill/drain plug holes? Thanks for any help!