DeWalt 1/2" drive electric impact wrench is your friend. If it can't get it off...you don't need it off.
I just picked up a DeWalt 292 electric impact wrench during the fathers day sale. its rated at 345ft/lb so this should be enough to remove the nut. I will find out soon as my steel socket comes in.
Which model did you use?
If the dewalt can't hack it, i'm going to try this next: Link
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