Chevrolet 2009 Silverado Owner's Manual page 510

Front Position - 1500
Models
4. Position the jack under the vehicle as shown. If the
flat tire is on the front of the vehicle (1500 Model
vehicles), position the jack under the bracket
attached to the vehicle's frame, behind the flat tire.
If the flat tire is on the front of the vehicle (all other
models), position the jack on the frame behind the
flat tire.
5-100
Front Position - All
Other Models
Rear Position – 1500
Models
If the flat tire is on the rear, for 1500 models position
the jack under the rear axle about 2 inches (5 cm)
inboard of the shock absorber bracket; for all other
models, position the jack under the rear axle
between the spring anchor and the shock absorber
bracket.
If you have added a snow plow to the front of your
vehicle, lower the snow plow fully before raising
the vehicle.
Make sure that the jack head is positioned so that the
rear axle is resting securely between the grooves that
are on the jack head.
Rear Position – All
Other Models