Spent over 3hrs in the K5 each direction this weekend going to the dunes. And yes I have a vibration. I couldn't feel it after my 4" lift, but then I never drove it that much, that long since doing it. I also just put a add-a-leaf in the night before we took off so maybe that was the difference. SO ANYWAYS, I already have the factory spacers between the frame rails and crossmember. So how much do I shim it? A washer or two? Another inch? My driveline angles don't look bad, but I can feel it. Thanks guys! Displacement, cubes, and did you say you drive a riceburner???