Is this a electric impact wrench? If so forget it. If it will not come off with a real AIR wrench (3/4 inch) with some air behind it? Snap-on use to make a "hammer wrench" (like Scott said) about 1-1/2 feet long. About 2 good licks with a slege hammer off it would come. I had one until it was stolen a few years ago. You could split the nut with a air chisel as a last resort. Soak it down with some PB Blaster no matter what you use. A little heat wouldn't hurt either.
I'm talking about a real compressor and not a little roll- around.
