I just replaced the axel in my and was putting everything back together. I got everything on exept the lower ball joint nut. I can't screw the nut on because the metal piece is spinning when I turn the nut. I cant get the nut on fare enough to put the cotter pin in.

 

Jack up the LCA until the ball joint seats firmly and impact the castle nut on until the holes line up.

Insert cotter pin or safety wire.