I know this is hard to diagnosis on the web, but I have an 87 XJ with over 300k miles and it runs great and handles tight.
The problem is when driving slow I can hear clanking noise from under jeep cannot see anything hanging loose.
I believe the u-joints are good. But it sort of sounds like play in the differential or maybe suspension bushings or maybe trans or transfer case?
Not sure how to check these items?
Has anyone had a similar problem?

 

Until you get it in the air and actually start looking, no one will ever know. So get dirty, it's fun!

 

Found the problem the front passenger side axle u-joint is failing and loose.

 

That many miles might as well replace axle u-joints and unit bearings, both sides.