Sounds also exactly like the problem I have on my truck. In 4wd and anything over 1/2 throttle it sounds like the drivers side wheel is trying to get away from my truck. I just went through and replaced everything on my front end from the steering, UCA and LCA bushings, balls joints and even changed the lift. My CV's are almost perfectly flat and yet the issue persists. Its gotta be in the diff. I just have to figure out what in the diff it is.