i have got what sounds like a wheel bearing going bad. a low pitched growl that increases and decreases with wheel speed only. it doesnt change with engine rpm. trans can be in gear or in neutral, strictly constant with wheel speed. i have jack up both sides of the front and theris no movement in the wheels side to side or top to bottom. It is a 4 wheel drive and i dont now much about the drive axles. all of the boots apear to be in good condition and nothing seems out of the ordinary. is there anything else up front that might growl liek that?