318 exhaust manifold bolts and nuts....

I ran into a problem. One of the studs that I need to use in order to hang the exhaust manifolds is stripped. When I tried to take it off using vice grips, it seems to be frozen in there. I tried spraying some wrench off in there, but it did nothing. Ay suggestions? I don't want to brake the stud off in the head otherwise I think I'll be screwed!