GMC Envoy Owner's Manual page 416

Envoy XL
The jacking equipment you will need is stored under the
rear seat (Envoy) or in the left rear quarter panel storage
compartment (Envoy XL). 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 1-5 for more information.
The tools you'll 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.
5-73