2003 GMC Sierra 1500 Pickup Owner's Manual - Page 336

Dolly Towing Two-Wheel-Drive Vehicles Two-wheel-drivevehicles 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 properly tow these vehicles, they should be placed on a platform trailer with all four wheels off the ground. 5. Release the parking brake only after the vehicle being towed is firmly attached to the towing vehicle. 6. -Arn the i ":ion off. s Four-Wheel-Drive Vehicles Use the following procedure to tow your vehicle: 1. Firmly set the parking brake. 2. Shift an automatic transmission to PARK (P), or a manual transmission to FIRST (1). 3. Securely attach the vehicle being towed to the tow vehicle. 4. 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. Shifting a four-wheel-drive vehicle's transfer case into NEUTRAL can cause your vehicle to roll even if the transmissionis in Park (P) for an automatic transmission, or if your vehicle is in gear, for a manual transmission. You or others could be injured. Make sure the parking brake is firmly set before you shift the transfer case to NEUTRAL. 4-55