How can I tell if my Transfer Case Module is bad and what signs should I notice?

What is your question?

This seems to have started a couple weeks ago, we noticed a winding type sound while driving down the road, a noticeable sound. This sound is constant and to me it is generating from the front portion of the vehicle like the 4WD system is not disengaging from 4WD HI to 2WD. I have consulted a mechanic and they seem to think it may be Transfer Case or Front Differential bearings. I really hope not, just can't afford this repair at this time, we just purchased this vehicle in Aug of 2012, used.