GMC 2004 Envoy Owner's Manual page 60

If your vehicle has a right front passenger's side impact
air bag it is located in the side of the passenger's
seatback closest to the door.
1-54
CAUTION:
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If something is between an occupant and an
air bag, the bag might not inflate properly or it
might force the object into that person causing
severe injury or even death. The path of an
inflating air bag must be kept clear. Do not put
anything between an occupant and an air bag,
and do not attach or put anything on the
steering wheel hub or on or near any other air
bag covering. Do not let seat covers block the
inflation path of a side impact air bag.