The only thing I didn't see someone mention is shocking the nut by putting the socket and breaker bar on and hitting it hard with a hammer in the direction of removal (sometimes the opposite direction helps too, but dont hit too hard , you dont want it tighter!) <img src="/forums/images/graemlins/zombie.gif" alt="" />

But then maybe your impact gun already did what my manual way already tried... <img src="/forums/images/graemlins/cyclops.gif" alt="" />