Helpes, get your hands on all the rear ends you can find and take out of them the spacer washers that go between the front pinion bearing and the machined shoulder in the axle housing. Those spacers were used in various thicknesses to adjust the fore-aft depth of the pinion mesh in the ring gear. Two of the spacers are used and varying their combined thickness provides the fore-aft pinion adjustment. The side to side ring gear adjustment is provided by the carrier bearing adjustment nuts.
To set up the gear tooth contact pattern get some titanium white paint from an art supply store and smear some on the ring gear teeth. Then rotate the driveshaft backward and forward to get the "drive" and "coast" gear tooth contact patterns and check the "backlash" (clearance) between the ring gear and pinion with a dial indicator. Then adjust the pinion spacer thickness and side to side location of ring gear carrier to center the contact pattern and get the backlash into the specified range any you're done!
