One problem related to noises during shifting has been reported for the 2003 Chevrolet Avalanche. The most recently reported issues are listed below.
Transmission started making growling and whining noise while attemping to shift into 4th gear, then started slipping in 4th gear. Shifting was also stiff or harsher than was normal for the vehicle prior to this. I took to dealer and was dismissed as their computer did not record any trouble codes. 1 week later, and only 65 miles travel distance, both 2nd and 4th gears completely failed, causing a complete overhaul and rebuild of transmission. Vehicle had only 14, 700 miles on it when problem surfaced. Dealership told me no known problems associated with this model vehicle.