Banging Chevy Tahoe

Hi all, seems to be some pretty knowagable people out there, so I would like tell you my problem and see if someone else has had this same problem. I have a 2005 Chev Tahoe with ALL WHEEL DRIVE. I have had the front differential overhauled and now notice a rattling and banging noise that sounds like its coming from the Transfer Case. This happens at different speeds 40 50 55, etc, only with no load on the engine. One time I heard a big bang and thought I would see parts on the road, but none showed. A rear end shop thought the "C" Locking Ring in the Case was broken and a gear was trying to go into 4 wheel when I was not accelerating. They pulled the Drive Shaft and said the "c" Lock Ring was OK> How ever with the all wheel drive, you do not put it into 4 wheel drive. I have all wheel and 4 low, plus neuteral on the dash. They have heard the noise and cannot dtermine where it is. I am thinking of pulling the transfer case and taking it in and have them open it. I had the Stability Light on all the time, but change the shocks and now it flashes periodically. I willl have to have it reset. Any one with any ideas? They would be really appreciated!

Probably a good Idea to have a look inside the transfer case. As far as the Stability light goes, that is usually a problem with the steering position sensor, at the base of the column.