the bolt is not that hard of material. I tried to work what was left of mine with heat double nutted the end. after two hours with the torch, the stub brok off. a standard drll bit is not long enough to reach from straight back. you will need to buy some drill bits that have a hex end on them ( that fits onto quick release drill adapters) then use that combined with a longer bit holder to make longer bit combination. Like is started off, the bolt isn't terribly hard and will drill if you can manage to get it started in the center. when you are done drilling it out you can retap it for a different bolt or a factory one.
Some say this is all due to corrosion, but i think the threads get galled from all the tourqe trying to move the axle. is yours on the left side? mine was.
good luck