01' Front end grinding - not clunking

Have an 01 Silverado 1500, 5.3l, ext cab, 4wd with 3.73 gears. Just drove down to Virginia and back to NY recently and heard/felt a grinding noise from the front end during the last 20 miles before I got home. It only happens when I turn the wheel even slightly to the left. When I looked underneath, I could see that the left output shaft seal on the front diff was leaking. I changed the seal and bearing with fresh 80-90wt fluid, but no change in the grinding/noise. When I drained the front diff fluid, there were some metal filings on the drain plug, but not a lot. The fluid was gray, but most had leaked out. Next I changed the half shaft/cv assembly. Again, no change. The front brakes look fine. Pads fine, rotors not scored, truck stops normally. Transfer case operating normally. Could the problem be in the front differential or the wheel hub bearing where the axle nut is? I'm thinking because of the loss of fluid at highway speeds, the problem might be in the differential. I don't think it is the intermediate steering shaft, but not 100% sure. Anyone else experiencing this?

lift the front wheels off the ground ..with the palms of your hands on the tire side wall rotate the tire ...if the tire has a vib/ruff feel to it when rotating your hub bearing is bad...remove the hub abs sensors look into the hole if you see rusted grease the bearing is gone...

1A AUTO has hub bearings at 90.oo ea with a 2yr warrantee [made in taiwan ] good quality bearings ...very good price ..