"If this doesn't work, get out Teddy-the-Torch and give it the heat."

Ugh!! Not a good idea and a real act of desperation. I would use a good penetrant oil (like KROIL) and soak it for a couple days before resorting to the hot wrench. You are likely to do more harm than good to surrounding components,

All the other suggestions are right on--especially the humongous breaker bar.

cheers.