I have rear driveline vibrations and drone. After researching previous post I checked the trans mount and there is a fair amount of movement. But then I grabbed the diff at the rear ujoint and I got a noticeable pop and you can see the movement from cap to cap even with the clips installed. This was a greaseable ujoint. Do the make a solid ujoint for the rear shaft to rearend yoke. This is a 99 Cherokee 8.25.

 

dana spicer 1310

 

greasable ones work just fine, as long as you check them every now & then