Best answer I can give...it varies. It varies between differentials as they are not all the same literally (manufacturing tolerances vary) and it varies between the skill level and capabilities of the individual.
You need some tools to setup properly. You need a way to measure bearing preload. This is done with a beam style or dial indicating torque wrench that can measure at least 50 in lbs.. I used a dial torque wrench.
You need a way to measure backlash, this is typically done with a dial indicator like in my picture above.
You need a way to measure your shims, so you could use a caliper or micrometer for that.
There are other tools available that can help you set up gears but the ones above are pretty much the basic "specialty" tools. You also need a "regular" torque wrench to torque down fasteners and something to help you hold the pinion yoke while you torque the pinion nut.
After you've made all the measurements and gotten everything "in spec" what ultimately matters is how the gears "pattern", how they mesh up together. At that point you simply have to put it together and take it apart to make shim adjustments (or adjust the adjuster nuts if you diff has those instead of shims) until you get a proper pattern (via marking compound, the yellow paint you see in one of my pictures above) and bearing preload.
I suggest doing what I did. Research research research. There's a ton of information out there, Some of it is great information, some of it is bogus information. You have to weed through it and sort it out. There's also plenty of books on the subject as well. If you are anal like me and this is your first time, be prepared to put your diff together and take it apart several times before you get it setup properly.
You need some tools to setup properly. You need a way to measure bearing preload. This is done with a beam style or dial indicating torque wrench that can measure at least 50 in lbs.. I used a dial torque wrench.
You need a way to measure backlash, this is typically done with a dial indicator like in my picture above.
You need a way to measure your shims, so you could use a caliper or micrometer for that.
There are other tools available that can help you set up gears but the ones above are pretty much the basic "specialty" tools. You also need a "regular" torque wrench to torque down fasteners and something to help you hold the pinion yoke while you torque the pinion nut.
After you've made all the measurements and gotten everything "in spec" what ultimately matters is how the gears "pattern", how they mesh up together. At that point you simply have to put it together and take it apart to make shim adjustments (or adjust the adjuster nuts if you diff has those instead of shims) until you get a proper pattern (via marking compound, the yellow paint you see in one of my pictures above) and bearing preload.
I suggest doing what I did. Research research research. There's a ton of information out there, Some of it is great information, some of it is bogus information. You have to weed through it and sort it out. There's also plenty of books on the subject as well. If you are anal like me and this is your first time, be prepared to put your diff together and take it apart several times before you get it setup properly.