Thanks for the info Tom, I have one of those big nuts on the light manifold for a 39 that is on its third round of PB blaster over the course of two weeks. And my 5' pipe for leverage isn't working on it either (not sure if that black stuff they filled the conduit with would 'weld' it together).
Anyway, I'll give this a try. Heat will be next. I'll let you know the results when I get back from vacation.