After hearing some noise for a few weeks. I went off to check wheel bearings and half shaft tests. This is for versatrack vehicles. Knowing that. Gm using a special lube for the rear diff. U need to change it and flush it. Here's how it goes. U have 2 plugs on the diff. Lower is your drain. Upper is to fill. Now to do this right please follow this. Drain the 2.1 quarts. Add royal purple 75 90 gear lube synthetic. 2.1 quarts. Yea .1. Now. Drive it in a figure 8 large ones 5 times. And smaller ones 5 times. Now repeat flush the rest of the old stuff out. Add another 2.1 and repeat the figure 8. Now the noise is gone. They recommend every 15k. I have 25k on the royal purple synthetic. It's a 80 dollar repair that can be done with an allen wrench I think it was a 13 mm. A half could work it is .011 thousands smaller but be careful not to strip the allen slot. This is what I did to fix it. And others did also. I'm posting this as my first post since I own one. And don't care for repair shops throwing parts at the car. This is a low speed growl that wheel bearings are very low percentage needing to be replaced since going left and right Boise is still there. The boots bot cut on the half shafts and no clicking it's the diff. Hope this helps. Again this is how I repaired my own car and do not take responsibility for what you do. This is how I fixed the rear noise in versatrack. Yes something this easy takes about an hour. The figure 8 are to move the lube around. And the sound goes away. Now u see alot of metal in the lube. You may have further issues. Hope this helps