My '05 Envoy with 4WD has a bearing noise up front. This happens in 2WD, as I have not driven anywhere recently where I needed 4WD. The noise will diminish when going around right hand bends, but no change when going left or straight. I was thinking it might be a front differential bearing, but might it instead be a wheel bearing? Starts at about 35 mph, continues up through 55, then quiets down above 60 mph. That fact alone tells me it's a differential bearing, but I have forgotten what bad wheel bearings sound like. Are they noisy at all speeds?