Not sure how/why the upper ball joint ended up with taller than usual castle nuts.
Trying to get a cotter pin in I think I over-tightened it.
I found a shorter castle nut and figured i'd break the spindle loose from the ball joint and reseat it with the new nut so it could be properly torqued.
Now when attempting to tighten it the ball joint shaft spins.
I tried using a pry bar to create pressure on the shaft seems to tighten but once pressure is released the shaft spins easily if you try to tighten further.

 

Unless you torqued them ball joint stud enough to stretch it, I doubt you damaged anything.

If the ball joint is used and has some wear, it’s common for the stud to turn easily inside the joint. As a matter of fact, you can turn them when new, it just takes a little more effort.

I routinely position the cotter pin hole in a location that makes assembly and future maintenance easier.

Having said all this, if there is any doubt about the safety of the ball joint, replace it. Is your safety and your car worth less than the 30 bucks and couple hours time to replace it?

 

Another thought on this..... Back in the 80's there was a Company that everyone knew for pistons called TRW. I have always used Moog parts when it came to suspension parts. My supplier was out of Moog Balljoints as there was a problem that I no longer recall. Anyway he sent some TRW Balljoints and the nut that came with the joint was oversize. So that is another area to check.

 

Been down this road many times, get yourself a good size pliers [will need help if you use a pliers] or big vise grips and hold the control arm down around the knuckle to seat the ball joint,, now you can tighten castle nut. make sure you ck the ball joint after it is tight to make sure it is ok..

 

It looks like what remains of TRW Automotive is owned by the German company ZF Group. At least it isn't Chinese yet.

I was surprised to see that something of this formerly great American company remained after the pillaging by Northrop Grumman for TRW's aerospace assets in the early 2000's..