I just installed a 1-ton tom woods custom drive shaft into my jimmy, and im not sure what shim i need in the rear axle. I've got 22 degrees on the driveline and 13 on the rear differential. The way i see it, when you rotate the rear axle you lift the front of the rear diff along with the bottom of the driveline. So i dont think i need the full 9 dergees of shim. But do you cut this number in half or is it a different ratio. The shop says to have them strtaight within 1 degree. please help.