A while back I put a Ford 9" in. All seemed well. Recently, I have developed a vibration. Now, it could have always been there and I just didnt notice, but its worse. When I ordered the rear they welded the supports on backwards! So I grinded em off and welded the leaf spring supports back on to about the way my stocker was. I probably was a little off. When its sitting flat, the 3rd member does by eye appear to be about a 1/2-1 degree down towards 8:00. If I raise the back end with air, vibration seems worse. If I lower as far as it will go, it seems to get better. I just balanced all tires at work on Saturday. Tires are perfect. Is it the Pinion Angle? I think its too low so I ordered 2 degree shims from Comp Engineering. Is the shaft out of balance? Any ideas would be appreciated...