[Dave at Pelican Parts]

Sounds like you're trying to remove the nut that holds the top of the shock rod to the rubber bushing that normally bolts to the fender well? If so, you can hold the rubber mount and washer still with a large set of channel-locks or a pipe wrench.

If you're talking about the gland nut that holds the shock body into the strut body, the pipe wrench should work.

--DD