Ok, I'm not sure if this is "working truck" safe or not, and I know the issue isn't rust since they were supposedly off recently, but how about some good ol heat? That is what I would try. Heat em up, tap em while they are hot and then try the breaker bar. I don't know if this will compromise the strength, but sounds like you may have to replace them anyway.... I don't think I'd go red hot unless you intend to re grease, and be careful of the shoes. Even moderate heat should expand things enough to give you the edge you need.
