help setting up gears

I am setting up FRPP 373 gears and wondering if it would be best to go right back with factory shims or what? I have installed all new bearings, seals, locker, axles, everything. And what is it that I see people talking about the numbers stamped on the gears that list the gear depth requirements or something along those lines. What are all the numbers stamped on the gears? I have installed it all once and the wear pattern did not seem right. I checked it and rechecked it with the ProForm Pinion Depth tool and it comes up to be .002 thicker shim on the pinion than the factory. Should I just use the factory, because the tool and myself could make that much error. What does anyone think, what would you do? I just want to make sure this thing dont whine and I dont break gears. The wear pattern from first assembly seemed a little to much toward the heel and not as deep in the teeth on the ring as it should be. It wasnt bad, but not as desireable as everything I read. Any advise is great.

Well see my factory shim is a .027 and when i put everything new back together with the old shims and set the backlash to .008 the wear pattern seems to be a little high on the teeth of the ring. I dont know if this is called face or flank but I would call it valley and peak. It is a little high, the wear pattern is running off the peak because it is too high. The only way to get the pinion to ride deeper down in the gear, more toward the valley of each tooth would be to lessen the backlash wouldnt it? I am already at lowest desired setting of .008. Any suggestions?