GMC 2004 Sierra - Manual (Page 353)

6. Shift the transfer case to NEUTRAL. See
Four-Wheel Drive on page 2-35 for the proper
procedure to select the neutral position for
your vehicle.
7. Release the parking brake only after the vehicle
being towed is firmly attached to the towing
vehicle.
8. Turn the ignition off and lock the steering column.
Loading Your Vehicle
It is very important to know how much weight your
vehicle can carry. This weight is called the vehicle
capacity weight and includes the weight of all occupants,
cargo and all nonfactory-installed options. Two labels
on your vehicle show how much weight it may properly
carry, the Tire and Loading Information label and the
Certification/Tire label.
{ CAUTION:
Do not load your vehicle any heavier than the
GVWR, or either the maximum front or rear
GAWR. If you do, parts on your vehicle can
break, and it can change the way your vehicle
handles. These could cause you to lose
control and crash. Also, overloading can
shorten the life of your vehicle.
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