Motorcycle Repair: 74 xlch main drive shaft nut, eye bolts, drive shaft

Question
I can not remove the main drive shaft nut from my 74 XLCH.  I was told a different thread pattern by two different HD dealerships which of course neither will touch it.  I've heated the nut and cooled the shaft and have tried an impact gun and a 18" breaker bar.  I have used eye bolts through an old chain and wratchet straped it to keep the sprocket from turning.  I need to change the seal and put a bigger sprocket on.  Any Ideas.

Answer
Never heard of one that wouldnt come off with a impact wrench, due to the fact that is how I remove them. It migth be that the last person that put it on got it cross threaded. If you cant get it off you might have to cut the nut to get it off withe nut breaker
Good luck and happy riding
Mike