Tahoe transfer case or transmission issue
 

Looking for input on this issue. I have a 98 Tahoe was backing out of driveway this morning and came to a stop. Tapped gas pedal and Tahoe won't move. Shift in neutral push it back in driveway. Won't mo e in forward or reverse but rolls fine in neutral. Can't figure out where to start. All fluid levels are good. Any ideas?