I had an '01 LB7 and I had the exact same problem as you. I asked a friend of mine who is ASE certified and the first thing he said was to check the batteries. Sure enough, one was leaking so I changed it out. The problem went away for about two years and the same side battery started smelling again. I changed it out and the smell wasn't there anymore. I then sold the truck so I didn't get a chance to check the alternator.