I am hearing a low pitch grinding noise that comes and goes when i am driving. Usually if i maintain a constant speed noise slowly starts to build up in a distinct pitch grinding noise. Its been doing this for about 3 months and car is driving perfectly with no problems. Does this sound transfer case related or transmission related? Anyone ever have this problem?

 

Plenty of videos on here and you tube of the tcase deathwhine. It usually sounds like a high pitch whine not grind. Possibly a wheel bearing?