I did this last year. My truck had rust, I pretty much destroyed the shocks getting them off. There is a metal piece under the nuts that is supposed to stop the shock from turning when you turn the nuts. The piece of metal is very weak and will bend/break, all 4 of mine did. You need something to hold the rod of the shock to stop it from turning. You cant get to the rod without messing up the metal cover attached to the top of the shock. Mine were worn out and I did not care if I messed them up. There might be an easier way, someone else should post up in the next couple of days.

Make sense? If not, ask more questions.