Hummer 2003 H2 Owner's Manual page 302

If you are using a winch to pull out another vehicle,
follow the winch manufactures guidelines and observe
the following to prevent damage to your vehicle:
D
If possible, have your vehicle anchored from
the opposite side of the winch to a solid,
immovable object.
If winching from the front, use both of the rear
recovery loops. If winching from the rear, use both
of the front recovery loops.
D
Put your transmission in NEUTRAL (N).
D
Use your regular brakes to hold your vehicle in
place and block the wheels to keep the vehicle
from moving.
4-74
NOTICE:
Using a power winch with the transmission in
gear to pull out another vehicle may damage the
transmission. When operating a power winch,
always leave the transmission in NEUTRAL (N).
If you are using a winch to pull out your own vehicle,
follow the winch manufactures guidelines for self
recovery and observe the following to prevent damage
to your vehicle:
D
Do not self recover your vehicle by wrapping the
winch cable around an object (such as a pulley block
or tree) and attaching it back to your vehicle's
recovery loops.
D
Always attach the winch cable directly to a solid
anchor directly in front of your vehicle to achieve a
straight line pull.