Chevrolet 2003 Silverado Owner's Manual page 464

Be sure the hoist end of the extension connects to
the hoist shaft (E). The ribbed square end of the
extension is used to lower the spare tire.
4. Turn the wheel wrench (H) counterclockwise to
lower the spare tire to the ground. Continue to
turn the wheel wrench until the spare tire can be
pulled out from under the vehicle.
If the spare tire does not lower to the ground, the
secondary latch is engaged causing the tire
not to lower. See "Secondary Latch System" later in
this section.
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3. Insert the hoist end
(open end) (F) of the
extension through
the hole (G) in the rear
bumper.
7. Put the spare tire near the flat tire.
5. The wheel wrench has
a hook that allows you
to pull the hoist
cable towards you to
assist in reaching
the spare tire.
6. When the tire has been
lowered, tilt the
retainer (D) at the end
of the cable so it
can be pulled up
through the wheel
opening.