I think I may have been unclear on which bolt(s) are stuck. It's the one's that go through the housing into the head, not the one's that house the thermostat. I was trying to be careful. Yesterday I twisted off the other one, I have been soaking in penetrating fluid and wiggling, it's kind of loose, but it looks like the bolts are still frozen to the housing and seem to be loose at the head. I'm going to try an ez-out which I'm sure will not be easy. I do have good access to the bolts. I guess cutting off is my last resort. Should have left well enough alone.