When trying to do an LS-1 brake upgrade, I removed everything from the front end, including spindles, which I had machined down and cleaned up.
When I went to re-install the spindle, the lower ball joint nut would not go on. Specifically, I would place the spindle on the lower ball joint, and I tried to torque down the ball joint nut, it would only go on so far before the "bolt" (for lack of a better word) coming out of the ball joint spun with the nut. I can't clamp it down or figure out a way to tighten the nut based to get the cotter pin in. Any thoughts?
Is my ball joint bad?

Jack up the lower arm until the stud seats in the spindle. You may have to tap the spindle down onto the stud with a hammer. It is a taper fit.

Thats one of those things that gets me pissed off beyond belief. Do what scblucam said and it will work