Symptoms of bad front driveshaft u-joint?

I was doing some work on the front of my XJ last weekend, and removed the front driveshaft for a little while. While it was off, I looked at the u-joint that connects the front shaft to pinion yoke. My first impression was that it was worn out, but then I realized that I don't know how to tell if it is worn out.

I twisted the caps by hand and it seemed to turn a little rough in certain positions while rotating, but don't know if that's normal. It is the original u-joint on my '99 XJ w/ 150,000 miles, and I am not aware of any noises or problems with it. How can you tell when a u-joint needs to be replaced? Is it as simple as looking for play while the driveshaft is connected, or is there more to it? Can you tell just driving down the road if something is wrong?

Cross, caps, needle bearings. Nothing in that combination should feel "a little rough".

Things to look for, DS installed: rust dust coming out of the caps, any kind of movement when pulled or twisted that is out of the ordinary.

Things to look for, DS pulled: pull the caps and check the needles and bearing surfaces for damage.

So as far as symptoms when driving down the road, there are none?

squeaking, clunking, grinding noises, etc.

It takes 5 minutes (if that) to pull the front end of the driveshaft off the diff and check, just do it :spin1:

Make sure you don't get any needle bearings stuck in the wrong spot (under the trunnion instead of around it) when you put the caps back.