Chevrolet 2005 T-Series Owner's Manual page 144

Here are specific towing instructions:
Towing Your Vehicle From the Front
(Front Wheels Off the Ground)
Before Towing
Block the rear 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.)
On vehicles with hydraulic brakes, release the parking
brake fully by moving the lever to the fully-released
position.
4-32
Towing the Vehicle with the Front Bumper
Removed
1. Remove the front bumper.
2. Connect and lock the lift chains to the front axle,
outside of the spring anchor plates as shown.
3. Connect the lift chains to the tow bar and raise the
tow bar until lift chain slack has been taken up.
4. Raise the vehicle to the required height.