I posted some better pictures with more exposure. The uniball pin has two slip over stoppers that allow the bearing to rotate without limiting the bearing rotation if that makes sense. The pins show rust on a portion of the break so I am certain that the pin cracks and then once it is cracked enough it just shears off.
A couple of the pictures are of the drivers side that I already replaced and is fully assembled the passenger side is the shots without the tire.
Ok I see it now. Its just what I was thinking it was.
The issue is you've got alot of angle in single sheer. The "stoppers" you're referring to are known as misalignment spacers. They do just as you described and let the joint flex beyond the diameter of the center bore of the uniball.
Whats your bumpstop situation? Id be willing to bet that on too much droop or stuff this is your weak point of the suspension trying to continue traveling past the given amount of flex in that joint. If thats the case you have a design issue and you will NEVER fix it by building that piece better.
A few given solutions may be to run a high misalignment spacer which will step down the through bolt size and require new machine but will allow for way more flex in the joint. Im no engineer so I couldnt begin to tell you what you need for a bolt size going through that setup but you're already breaking shit and for all intensive purposes loosing a balljoint while driving, and thats dangerous.
You could uncrank the torsion bars which should reduce the preloaded angle on balljoint too.