If you're planning to disassemble a used differential, try to get a good gear contact pattern before changing any adjustments or removing any parts. The traditional way to check tooth contact is with a mixture of white lead (lead carbonate powder) and linseed oil. Anything with the word "lead" in it gives snowflakes a case of the vapors, so finding white lead these days is almost a lost cause. It's also possible to check tooth contact patterns with Prussian blue. Paint several teeth with the indicator dye, have a helper grab the input yoke with a pair of heavy gloves to provide some resistance, and spin the ring gear back and forth rapidly to spread the dye. The tooth contact pattern will be obvious by the places where the dye is wiped away. Also check the backlash before disassembly. There's no guarantee you'll get it back together in the previous relationship, but at least you'll have a pattern to shoot for!
Jerry
