my gearbox boot is shot, but everything inside seems nice and tight....no wiggle or play when I move the rods. The question is this: before I put the new boot on, what kind of grease to I use on the ball joint? Same as CVJ grease??

my choice would be

"Lockease" a lock lubricating liquid with graphite.

 

Since this area will see road slush, I like using a lubricant that

will not hold dirt - thus the graphite.