When we put the front leaves on, we had to make new shackles and also drill a new shackle-mount hole. The new shackle was 2 inches longer, plus the shackle-mount hole in the frame was about 2 inches lower than the original. When you think about it, it's obvious: The pinion was going to be rotated down, along with the knuckles. Not only did this give a bad driveline angle, but it also gave us scary caster issues. The front wheels were now trying to steer under the truck when we cranked the wheel. To address this problem, we went back to Deaver to get some 4-degree bronze shims. This rotated the axle back up and alleviated much of the pinion angle and caster problem.