two ideas:
1. Hold the breaker bar and let someone smack it with an 8lb sledge. That has worked for me.
2. Need to be careful with this one, but I have done it a few times. Wear appropriate protection. Put the socket on the nut so that the breaker bar is pointing to the 4:00 position. Then place a floor jack under the end or the breaker bar. You might need to lower the front of the truck to do this. Then jack up the breaker bar. If you get to the point where the front end lifts up off the jack stands, you have several thousand pounds of weight on the bar and nut. If that doesn't break it loose, let it rise until it is about 1" above the jack stands and push that down on the fender. This has worked for me every time.
