Thanks for the reply John,jzeiler said:There are a few things you can do to assess the condition and determine the amount of use it has had. The pivot bearings for one - do they feel "smooth" when you rotate them with a finger? Are they "notchy"? If they are smooth then it has had little use. If they are notchy then it has a few miles but that is normal for these bearings. I have replaced them on every drive I have removed.
The stiffness of the U-joint in the drive shaft end. Loose here means lots of use. You can remove the 7MM bolts around the perimeter and open the case with a rubber mallet and look for signs of dark residue which could indicate aluminum wear (not so good).
Also get a general look at the big bearing but with out cutting it open it is hard to assess condition. Biggest failure to date on 05 and up rear drives is the taper bearing coming loose on the crown wheel assy. You can give it a tug when you open it to see if that is still tight.
Other than just preemptively replacing bearings (not really recommended on this one) that is about all you can do.