truck has a receiver hitch tube front driveline. Trying to figure out this noise, it snds like tires rubbing on a mud flap. Truck will creep fine without noise but say at 5-10 mph in 4wd with hubs locked it makes the sound of tires rubbing. Truck makes no noise in 2wd (hubs unlocked) with tcase in low or high 4wd. Ive jacked the truck up and spin both tires, and spun the diff driveshaft flange by hand and all feels good. Is it just the tube driveline? thanks guys