If you're still out there, what did you finally find? I have same problem on 86 Sammy. I have checked allignment, tie rod ends, kingpin play, wheel & tires for roundness, wobble, and balance. I replaced the stabilizer and shocks. I have even added a wedge to improve axle angle, and while helping for a short time, the problem came back with gusto. The manual says the seals on the pivot for the axle are critical, but mine seem OK. Does anyone know if there is a torque measurement for the pivot with the seal installed and loose?