Usually they are not that difficult to remove. I use a nut in place and a big heavy hammer to place a slow blow. If you have to resort to drilling, you may want to heat the stud a bit and let it cool naturally. That may soften it up a little.

1951 GMC 1 Ton Flatbed -- It is finally on the road and what a great time I have driving it!
1951 1 Ton Completed

My Chevy Master 4 Door is on the Road!