Transmission problem
1997 Oldsmobile Bravada 6 cyl Four Wheel Drive Automatic 152000 miles

My car has the Select Trac. We had our first major snowfall of the season and I realize that I don't have 4 wheel drive when I need it. Do I have a transmission problem?

Not transmission but possibly transfer case related. You would need to test the system to discover where the problem is. It is possible that the problem is related to the ABS system or to a problem with the front drive section in the transfer case.