Replacement parts and keys can be bought from custom or restoration websites and catalogues.
I suggest getting a matched door and ignition set. The link provided is for Rock auto, I use them for some Jeep stuff, it is a place to start.
Otherwise a locksmith can rekey some locks, and a good one can reconstruct a key from the cylinder, but those options are all more expensive than just replacing the ignition cylinder and lock cylinders.
I can recommend you to call a locksmith. And stop losing your keys.
That requires the dealer's scan tool.
Assuming you lost the keys, write the vehicle identification number down on a piece of paper, take that and proof of ownership to your local Chevy dealer and they can reproduce new keys for you.
Don't replace anything. The dealer can make you new keys by using the Vin # on your vehicle.
Contact your local Chevy dealer. Or contact OnStar, if you have it. Chipped keys range in price from $35.00 to $160.00. There will also be a service fee to re-program it.
Number for lost keys
No there isn't one except for timing
The duration of The Legend of the Lost Keys is 1200.0 seconds.
Go to Chevy dealer with proof of ownership and VIN. They can cut you a fresh key.
The Legend of the Lost Keys ended on 1998-03-23.
The Legend of the Lost Keys was created on 1998-01-12.
Locksmith