I had one on my wife's Sebring. I have no idea why there was one on a car with 50,000 miles (when we got it), but the adjusting nut stripped the body of the joint. I'd never use one again...
I think they are what I use to raise the pivot point on the UCA on certain applications. It is a housing with separate stud. By using the available longer studs, the roll center can be lowered.
These are nos ball joints. I don't know how old they are by I'm guessing at least 20 years old or more. The boxes say copyright 1962. It seams like the adjustment controls how tight they are.