Stop-Bump issue on pre-96's?

[S-FLY1]

I don't have to grease the slip joints because they're supposed to be self-greasing from the t-case in these models. I put in Dextron ATF, not 80w90 as I first thought it took. I'll have another look at the u-joints.

 

[S-FLY1]

Just to update, I took my XJ in to a jeep mechanic and he gently file the splines on the inside of the drive shaft that goes into the slip yoke. The clunking/bump went away, but came back mildly. About 80% better than what it was.