GMC 2011 Sierra Denali Owner's Manual page 434

10-90 Vehicle Care
Dolly Towing
Front Towing (Front Wheels Off
the Ground) Two-Wheel-Drive
Vehicles
Notice: If a two-wheel-drive
vehicle is towed with the rear
wheels on the ground, the
transmission could be damaged.
The repairs would not be covered
by the vehicle warranty. Never
tow the vehicle with the rear
wheels on the ground.
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.
Front Towing (Front Wheels Off
the Ground) Four-Wheel-Drive
Vehicles
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.