2004 GMC Sierra 1500 Pickup Owner's Manual - Page 504

Front Position All Other Models Rear Position 4. Make sure the jack head is positioned so that the rear axle is resting securely between the grooves that are on the jack head. Turn the wheel wrench clockwise to raise the vehicle. Raise the vehicle far enough off the ground so there is enough room for the spare tire to fit under the wheel well. 5-104