Chevrolet 1997 Monte Carlo Owner's Manual page 62

The ignition keys are
The door keys are for the
When
a
new Chevrolet is delivered, the dealer removes
the plugs from the door keys and gives them to the
first owner.
The ignition keys don't have plugs. Your Chevrolet
dealer or Roadside Assistance has the code for
your keys.
Each plug has a code on it that tells your dealer
or a
qualified locksmith how to make extra door keys. Keep
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the plugs in a safe place. If you lose your door keys,
you'll be able to have new ones made easily using
these plugs.
If you need a new ignition key, contact your Chevrolet
dealer who can obtain the correct key code, or, in an
emergency, call Chevrolet Roadside Assistance at
1-800-CHEV-USA (1-800-243-8872).
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NOTICE:
Your Chevrolet has a number of new features
that can help prevent theft. But you can have a
lot of trouble getting into your vehicle if you ever
lock your keys inside. You may even have to
damage your vehicle to get in. So be sure you
have extra keys.