Originally Posted by
hambone
Clearance between ring and pinion gear. Or play. The other kiss of death is putting driveshaft on without holding pinion against bearing.
Yep that will do it every time as well.
Another note, as the gearbox gets older and more beat up, it also will become more flexible which causes even more trouble. That's why it is a good idea to replace them pretty often. The aluminum bearing inserts do help some, but the gearbox still flexes.
