How can i get this off?

[Jeff65]

First, I'd try using a chisel and sledge or better yet air chisel to break the nut off. Go straight into the nut from the bottom side. I'll bet the nut cracks fairly easily with an air chisel. If you don't like this approach, I would drill it out from the bottom. Center punch the ends of the shock, use a hardened drill bit then drill right up the center of nut. Even if the drill drifts off center it doesn't matter much because you're neither trying to save the shock or the nut.