Did you maybe break the retaining clip that goes on the frame and it's now spinning?
Two of my clips broke when I took my rear shocks off (factory shocks at 162,000) and I had to use nuts+washers+bolts to secure the new shocks to the frame. I dropped new bolts through the top of the frame and screwed nuts on from the bottom.
I think I remember using vice grips to clamp onto the frame clips that broke. It was a PITA, but not as bad as doing the front shocks without a stubby 18mm wrench..!