The threads on this subject and possible causes are long and filled with good thoughts from distinguished folks (do some searches on Dana 60 Death Wobble for more background). The final fix for me seems to have come with the replacement of the nylon bushings on the upper king pin. After examining the old ones closer, the bottom view best describes what is happening: These are both the old ones (sorry, didn't photograph the new ones). I tried to take the photo centered to eliminate distortion. Looking at the thickness going around you can see the variation. Especially evident is the difference toward the outside (where the key is). This would stand to reason since the pressure would be against this point with the weight of the vehicle. It also makes sense that wider wheels are going to worsen this. I have seen posts where some problems have gone away with re-balancing tires; IMHO, this was taking away the trigger, not eliminating the cause (mine was triggered by bad bumps on one side or by braking with rotors that should probably be turned). Enough said, just wanted to share my solution (that has taken nearly a year to come to... of course the truck has been down for various other mods a lot of that time, too /forums/images/graemlins/grin.gif ) BTW, I tried to replace the King Pin while I was at it... 5 foot cheater and neighbor searching with traction and me beating on a 1' wrench with a sledge at the same time produced nothing but broken tools. A tip though, my 7/8" lug nut with a 7/8" socket made a great allen's head! Hopefully this will help someone else. I had passed by this after an inspection when installing the axle.