I need to find a Seattle area shop that can service the 3.9 diff on my 2005 C6 Z51. I'm pretty sure the dealership is out because they aren't stock gears, they would just want to replace them with stock ones.
Since the issue is a very slight whine at this point, I really want to find a shop who will be able to troubleshoot it rather than just replacing the whole diff gearset...$$$