2008 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 149

{CAUTION: It can be dangerous to get out of your vehicle if the shift lever is not fully in PARK (P) with the parking brake firmly set. Your vehicle can roll. Do not leave your vehicle when the engine is running unless you have to. If you have left the engine running, the vehicle can move suddenly. You or others could be injured. To be sure your vehicle will not move, even when you are on fairly level ground, always set the parking brake and move the shift lever to PARK (P). {CAUTION: Four-wheel drive vehicles with the transfer case in NEUTRAL will allow the vehicle to roll, even if the shift lever is in PARK (P). So, be sure the transfer case is in a drive gear - not in NEUTRAL. Always set the parking brake. Follow the proper steps to be sure your vehicle will not move. See Shifting Into Park on page 2-51. If you are pulling a trailer, see Towing a Trailer on page 4-55. 2-55