Make shure the threads are really clean leading up to the nut, give a good spray of wd 40, and duck oil. Plave ya socket an bar on as close to the bodu of the car as u dare, the place your long bit if scaff pipe over it, have it about a foot off the floor and stand on it, even jump up and down on it, the shock shud get it undone. Do you have an air gun handy?? failing that, depending what your doing, show it sum heat, but be careful not to melt gators etc etc p.s does it have a indent where the nut is bashed into a groove on the threads, a locking mechanism?