the angle is the difference between the pinion/trany angle and driveshaft angle ...not the trany vs pinion.
So if your trany is at 2.5 down and the driveshaft is at 6 ... you take 6 - 2.5 = 3.5
then measure pinion angle... lets say 4 down for that as well.. your driveshaft is still 6 so..
6 - 4= 2
you would need to shim the rearend.
If you have a negative angle you would add the numbers
