Chris,
"Dana" factory gears are usually marked with a number i.e. "0" +1,-1,+2,-2,etc. That refers to the change required from the "base shim". So if I have a +1 gear and a .029 shim, that carrier would use a .028 on a zero gear. If the other is a +3 and the shim is a .032 "that" carrier would use a .029 for a zero gear. If you aren't working with genuine Dana gears , that all goes out the window and you have to revert to the pinion depth method. A Dana is one of the most time consuming and frustrating styles I had to deal with when I did them professionally.
Randy