When working on my Jeep, I often use products designed for applications outside of the automotive industry to cure a problem I am having. An example would be Rector Seal Blue, a pipe thread sealant that I have used on bolt or stud threads that thread into an engine water jacket. It is a Teflon based sealant that lubricates the threads preventing galling, is not effected by heat, oil or water. If need be, parts can be disassembled at a later date without issue. I wonder if a light coating of this on the D18 output shaft splines would work to cure that pesky shaft to yoke oil leak.