The crush sleeve is to set the preload on the pinion bearings, and the correct backlash for the gear set is usually scribed on the crown gear on aftermarket sets. The typical lash that I use is .008" and I check that at four equally spaced places around the gear. Get the right paste to check the contact pattern as well. The pinion depth is adjusted to get the right contact pattern. Break it in by running it with the rear end on jackstands for about 1/2 hour, shutting it off and checking it periodically to see if it gets hot, then treat it right for about 500 miles, just like an engine.