You can't really check the preload properly with the ring gear in the housing. But it's not an option to pull the ring gear at this point, that's more trouble than you need. There isn't enough backlash between the pinion and ring teeth to allow a proper measurement of the bearing preload when it's all together. Since you also can't just put the nut on the same number of turns, the other option I've heard mentioned is to put the nut on and only tighten it to a very low torque, about 10 lb-ft, and then stake the nut. This avoids crushing the crush sleeve any more and creating too much preload. Theoretically, once the bearings are broken in, there really shouldn't be any preload on them anyways.

I've done the low torque technique on one of my diffs when I had to replace a pinion seal, and the gears were still running great two years later when I pulled them out to change ratios.


edit: I suppose if you compare Roger's answer and mine, the clear winner is to just torque the nut to somewhere between 10 and 90 lb-ft and stake it well. <img src="/forums/images/graemlins/lol.gif" alt="" />