GMC 2008 Envoy Denali Owner's Manual page 377

CAUTION: (Continued)
3. If you have a four-wheel-drive vehicle, be
sure the transfer case is in a drive
gear — not in NEUTRAL.
4. Turn off the engine and do not restart
while the vehicle is raised.
5. Do not allow passengers to remain in the
vehicle.
6. Put the wheel blocks at the front and rear
of the tire farthest away from the one
being changed. That would be the tire on
the other side, at the opposite end of the
vehicle.
When your vehicle has a flat tire, use this as a guide to
assist you in the placement of wheel blocks.
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