GMC 2004 Sierra - Manual (Page 504)

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.
Front Position All Other Models Rear Position
5-104