Get a:
Drill
Tempered drill bits, relative in size to the bolt extractor
Bolt extractor
Torch
Lighter
Drill a hole as straight and centered as possible in the top of the stud with a drill bit no larger than the bolt extractor you will be using. Heat up the surrounding metal (around the stud, not the stud if you can at all help it). This will cause the metal to expand and losen it's hold on the stud. Then use a bolt extractor and it should come out. Worked great for me taking off rear axle bearing spindles from 17 y/o trailing arms!