GMC 2009 Envoy Denali Owner's Manual page 286

Four-Wheel-Drive Vehicles
Use the following procedure to dolly tow a
four-wheel-drive vehicle from the front with the
rear wheels on the ground:
1. Attach the dolly to the tow vehicle following the
dolly manufacturer's instructions.
2. Drive the front wheels onto the dolly.
3. Shift the transmission to P (Park).
4. Firmly set the parking brake.
4-42
CAUTION:
{
Shifting a four-wheel-drive vehicle's transfer case
into N (Neutral) can cause the vehicle to roll even
if the transmission is in P (Park). The driver or
others could be injured. Make sure the parking
brake is firmly set before the transfer case is
shifted to N (Neutral).
5. Shift the transfer case to Neutral. See "Shifting into
Neutral" under Four-Wheel Drive on page 2-28.
6. Secure the vehicle to the dolly following the
manufacturer's instructions.
7. Release the parking brake only after the vehicle
being towed is firmly attached to the dolly.
8. Turn the ignition to LOCK/OFF.
After towing, see "Shifting Out of Neutral" under
Four-Wheel Drive on page 2-28.