GMC 2005 Envoy Owner's Manual page 400

Envoy XL/Envoy XL Denali
To release the jack from its holder, turn the knob on the
jack counterclockwise to lower the jack head. See
Rear Seat Operation on page 1-9 for more information.
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The tools you will be using include the wheel wrench (A),
wheel blocks (B), extension(s) (socket end) (C),
handle (jack end) (D), and jack (E).
The following instructions explain how to remove the
underbody-mounted spare from underneath your vehicle.
Notice: If you remove or restow a tire from/to the
storage position under the vehicle when it is
supported by a jack, you could damage the tire
and/or your vehicle. Always remove or restow a tire
when the vehicle is on the ground.