I was sitting in stopped traffic on a street and as I hit the gas to move, I heard a loud sound and then nothing but grinding. As I hit the gas the grinding got louder. Truck wouldn't move under power at all. Luckily I was moving enough to roll to the side of the road. I wonder if my chain snapped in the transfer case...but I thought it was a direct connection through it to the rear axle. I had an issue with the rear of my overdrive unit breaking off and the transfer case sitting on my skid plate for a while. Could the splines of just worn off over time and finally given up? That's the grinding sound I hear? I'm going to try and pull the transfer case tomorrow and take a look. Also, is replacing the overdrive unit as easy as pulling off another one and sliding it on my transmission? Kinda amazes me that the transfer case doesn't get any support other than being bolted to the transmission. Any thoughts are appreciated!