Chevrolet 2003 Impala Owner's Manual page 97

Steering Column Shift Lever
1. Hold the brake pedal down with your right foot and
2. Move the shift lever into PARK (P) like this:
set the parking brake.
Pull the lever toward you.
Move the lever up as far as it will go.
3. Turn the ignition key to OFF.
4. Remove the key and take it with you. If you can
leave your vehicle with the ignition key in your
hand, your vehicle is in PARK (P).
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