INFERNO

I have a 93 Z that I am installing my rebuilt motor and t56 swap. I am trying to put the suspension together and when I try to install the castle nuts on the lower balljoints and the tierod ends, the stud in the joint keeps spinning. The nut will not thread too far on the stud. I tryed "shocking" them on with quick movements of the socket and a wrench. I just rebuilt the entire suspension on this car about 6K miles ago with all Moog parts. Everything except the upper balljoints were replaced. Is there anything short of replacing them? They are still very tight moving back and forth.