Originally Posted by IndianaJo

I'm a food plant mechanic, I have stripped out dozens of allen head bolts, both with pro grade Bonrus ball head wrenchs, also Proto brand allen adapters. The most succesful procedure is to soak the bolt with penetrating oil, install a Proto socket adapter attached to an air impact gun, heat the steel around the bolt, re-oil,check gun direction, pull the gun trigger. In a food plant where caustic and acids are used to clean, the bolt head strips 1/3 the time. I also lived on the gulf coast as a youth, there was a higher percentage to stuck bolts on my car due to salt. Allen head bolts are harder than "high speed" drill bits, if you try to drill with that you may have to resharpen a couple of times. Cobalt drill bits that are hard enough drill allen bolt steel in one pass run about $30 in the 9/16" size. It takes a lot of chest strength to drill a 9/16 dia bolt head, you'll get no weight advantage drilling up from the floor. I don't have this chest strength, beefy guys can drill a big bolt off in 1/10 the time of wimps like me. Mostly when allen head bolts strip we tried to cut the head off with a die grinder, but you can't do that on a bolt head buried in a frame rail.
Oh by the way, my chair caster shock absorbers make the engine vibration acceptable to me. If you have multiple cars, taking the shock absorbers off another car is a fine idea.