Brian, soak those nuts down real good with either Kroil, or PB Blaster. If that doesn't work, heat up the nuts with an O/A torch. Sometimes those are studs and not bolts, and you really don't want to replace those. They're pretty tough, just don't use too big of a cheater. A 1/2" airdrive works nicely too.
Good luck, I find little joy in working like you're about to. I used to like doing things like that, that was before arthritis, tendonitis, and a couple other itis's starting getting me. And I'm a young 54!!
PS, A nice supply of adult beverages helps too!!!