One problem related to automatic transmission column shift has been reported for the 2003 Chevrolet Avalanche. The most recently reported issues are listed below.
When ignition key is in accessory position and vehicle is in park, the brake/shifter interlock is disabled, allowing the shifter to be accidentally shifted into neutral. If the vehicle is on a slope vehicle immediately starts freewheeling downhill. Fortunately I was able to apply the brake and stop without incident. . .