GMC 2013 Sierra Denali Owner's Manual page 394

6. Turn the ignition to LOCK/OFF
and remove the key
steering wheel will still turn.
After towing, see Shifting Out of
Neutral under
for the proper procedure
to take the vehicle out of the Neutral
position.
the
Two-wheel-drive vehicles should not
be towed with the rear wheels on
the ground. Two-wheel-drive
transmissions have no provisions
for internal lubrication while being
towed.
To dolly tow a two wheel drive
vehicle, the vehicle must be towed
with the rear wheels on the dolly.
See Rear Towing (Rear Wheels Off
the Ground) later in this section for
more information.
Use the following procedure to dolly
tow a four-wheel-drive vehicle from
the front:
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.