Body lift

"Where there's a will, there's a way"

Let's hope so. I admire the optimism. Just hoping it's not too far gone.

Use a suitable powered wire brush to remove all the corrosion. Shock treatment ie thump with a lump hammer ( don't go overboard ) usually helps. If possible reshape hex. with angle grinder. If this is possible try suitable single hex. socket with loosen/tighten motion to further break bond. Use heat only if sure you wont set fire or damage something. Windy gun not advised as can be to abrupt. You want to build up torque level to just enough. There are specialist sockets (refer google outlets ) that are designed for this situation. Mole grips and pipe grips are other possibilities.

Roger

Like Lambert says wd40 or similar 2 to 3 time a day over a few days
Wire brushing occasionally
I have removed them from 2001 and 2004 slow and steady
Loosen tighten wire brush some copper slip grease and repeat

I got mine off on the Boogie, the buggy's donor is a 1999 and they came off eventually to get the JimnyBits sidebars on as they mount to the chassis rail in the middle and the four body mounts either side and under the doors...

I replaced the nuts as a matter of course...

there we go, that's the state of them. Some are likely to need replacing and theres a fair bit of welding to do on the body, including sills and slam panel. Chassis will be ok, but that's quite a substantial thickness of metal, just the body mounts are starting to look like weetabix.