GMC 2009 Sierra 1500 Crew Cab Owner's Manual page 506

Extended Cab
A. Wing Nut
Retaining Tool Kit
B. Tool Kit
5-96
C. Wheel Blocks
D. Jack
E. Jack Knob
For regular cab models, the equipment you will need is
behind the passenger's seat. For extended and crew
cab models, the equipment is on the shelf behind
the passenger's side second row seat.
1. Turn the knob on the jack counterclockwise to lower
the jack head to release the jack from its holder.
2. Remove the wheel blocks and the wheel block
retainer by turning the wing nut counterclockwise.
3. Remove the wing nut used to retain the storage
bag and tools by turning it counterclockwise.
You will use the jack handle extensions and the wheel
wrench to remove the underbody-mounted spare tire.