Which rear shock bolt? The uppers are studs. You should be removing one nut, not both. Loosen the other and the slotted bar pin on the shock mount will slide out. If these are giving you trouble, bend away at the tub of the jeep just above the frame so you can get a wrench in there. If it is the lower side you cant get off. Should be trying to loosen the nut, not the bolt. Never the bolt. Once the nut is loose, then you can use a pry bar and try and rotate the seized nut free. If neither works, cut the bolt head off, cut the nut off, use a pry bar to spread the lower shock mount a bit and run a hacksaw blade between the shock bushing and mount to cut more of the bolt so you can pry it out.