Worn axle u-joint and bearings
 

I got under my front end to fix the death wobble that I've encountered on the last couple of drives, and found disturbing news. The passenger side axle u-joint is worn out and needs replacing. I also noticed that the plastic dust cap on the axle is separated from the knuckle(or the shaft hole that it is supposed to seal) by about 1/2 inch. When I turn the shot u-joint the axle shaft can move up and down in the shaft hole.
Do I have more going on than just the worn out u-joint? Could there be worn out seals or bearings inside the tube the axle shaft runs through on its way to the differential?
Also, the big question I have is: Does this mean that I have some problems inside the differential, because I don't want to tear further into the axle to find out that I have to put it back together and take it to a shop.
Am I right in assuming that since I'm driving in two-wheel drive when the death wobble occurs that this axle issue is not the cause?
Thanks for any of your help.

I would bet the axle movement is because of the busted u-joint and unless you are leaking fluid the oil seal inside should be good. I would just replace the u-joint.

I doubt the u-joint has anything to do with the death wobble. If you have a lift, check the caster angle, that’s what caused mine on my DD.

I agree with CJXJ. Just do the joint for now. You will still feel issues with the front drive train even in 2wd as it's all interconnected. The front axle still has some engagement where you wouldn't feel many front problems if they had locking hubs rather than automatic hubs.

The death wobble can be from a few components. I had it on my former '97 just from the steering stabilizer going bad. It may not have been THE death wobble, but it sure felt like it. Hopefully, you should feel an improvement after replacing the u-joint alone.

Recommendation. Do the u-joint on the other side also. From experience, if one side goes, the other side is not real long from following. I'm sure there are some differing experiences, but not from my perspective. Might save you some issues down the road.

I just did my rear diff u joint, so I'm waiting for the other three to go lol