hammer and chisel the bastard off without fuking up the thread but by the look of your previous butcher work maybe let someone else without parkinsons have a go at it.
Maybe heat around it then freeze the nut.

you can try using bolt extractor.

http://www.autozone.com/autozone/acce ... t/Bolt-Extractor/_/N-25qe

my practice is to make sure gbox fill and drain plugs can come out before i put a box in.
fill bolt was tight, but got it off easy enough. drain pulg was slightly rounded and tight. looked like some kind of sealer on it. sprayed wd40 and let soak for 1 hour. tried to undo, no go. thought nip it up 1/8 turn then try. no good. thought id try tapping with my newly aquired nylon hammer to shock then breaker bar, no good and it strited the block bit in the pulg!!! F@%$#



now how do i get it out? just weld a block of steel or a socket onto it and try crack the seal? heat up the nut with a butane torch as well?
ive got a spare plug on another 63a... the measure the same, so should work. im at a loss now. it was rounded slightly before but now ive stuffed it... help!