GMC Sierra Denali Classic 2007 Owner's Manual page 411

Front Position - All Models Rear Position – All Models
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.
5. 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.
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