Forgive me if I'm an idiot, but this isn't a bolt and nut clamping metal together, right? Isn't the ball joint threaded shaft itself tapered (if that's the right term), and the nut just pulls the tapered bolt into a consistently sized hole where friction does the work? I think the deal is recentering the "neutral" position of the threaded shaft on the ball joint once the truck is lifted via torsion bar crank. The spacer simply positions the hole so that the shaft is perpendicular to the joint.

I'm probably wrong, but I don't think that stretching the bolt in a friction fit situation is going to happen here...

Please educate me.