GMC Sierra 2000 Owner's Manual page 271

CAUTION:
The recovery hooks, when used, are under a lot of
force. Always pull the vehicle straight out. Never
pull on the hooks at a sideways angle. The hooks
could break off and you or others could be
injured from the chain or cable snapping back.
NOTICE:
Never use the recovery hooks to tow the vehicle.
Your vehicle could be damaged and it would not
be covered by warranty.
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