The top nut and locknut refuse to budge; any attempt to turn them just turns the whole top of the old shock. I started to think about hacksawing through the shaft just under the nuts, but didn't want to commit to this (and thus taking the car off the road) until I knew I would be able to remove the bottom bolts. This was where the fun started...

I managed to remove the nylock nuts on both sides, however no amount of release fluid and banging with a hammer will move the bolts. I think they are rusted into the lower bushes of the shocks, thus preventing them from sliding out. The bolts and spacers appear to be available from SJs (waiting for confirmation), so I was thinking of cutting through the bolt and spacer just to either side of the shock bottom bush.
Does anyone have any less destructive suggestions I can try first to remove the bolts?