(vice grips, socket, soak it with liquid wrench)
nothing will budge this thing.

Any suggestions?

I see BP Blaster suggested I am not familiar with that product. I am
familiar with Kroil/AeroKroil from kanolabs.com , which to me is FM*!
Try taking apart a diesel turbine mount Impossible without this stuff.
It is a superpenetrant, Spray on a few times a day, and tap with a
hammer, or try heating the block (heat lamp a few hours), and dry
iceing the bolt, guaranteed removel. Just be patient, and save the
grinder/dynamite/etc for last resort. Good luck, time works. Please
take reasonable fire precautions.

http://www.kanolabs.com/

*friggin magic
Den