GMC 2003 GMT560 T-Series Owner's Manual page 152

After Towing
1. Block the rear wheels and install the axle and
propshafts.
2. Check for proper phasing of universal joints.
3. Apply the emergency brake system before
disconnecting from the towing vehicle.
4. Check and fill the rear axle with oil as required.
Towing Your Vehicle From the
Front (All Wheels On the Ground)
Your vehicle may be towed on all wheels provided the
steering is working. Remember that the power brakes
and power steering will not have power assist. Vehicles
with air brakes will not have brakes. There must be a
tow bar installed between the towing vehicle and
the disabled vehicle.
Before Towing
Block the wheels of the disabled vehicle. On vehicles
with air brakes, release the emergency brake system by
compressing the brake chamber springs as outlined
in this section. (This is to prevent the possibility of the
emergency brake being applied during towing.)
4-34
On vehicles with hydraulic brakes, release the parking
brake fully by moving the lever to the fully-released
position.
If there is damage or suspected damage to the axle(s),
remove the axle shafts. Cover the hub openings to
prevent the loss of lubricant or entry of dirt or foreign
objects.
After Towing
1. Block the rear wheels and install axle and
propshafts.
2. Check for proper phasing of universal joints.
3. Apply the parking brake system before
disconnecting from the towing vehicle.
4. Check and fill rear axle with oil as required.
Towing Your Vehicle From the Rear
(Rear Wheels Off the Ground)
Before Towing
Secure the steering wheel to maintain a straight-ahead
position. Make certain that the front axle is not loaded
above the front axle Gross Axle Weight Rating (GAWR)
as indicated on the vehicle's Gross Vehicle Weight
Rating (GVWR) label. See Loading Your Vehicle
on page 4-37 for more information.