[Six Banger]

I am looking to theft proof a little and was wondering if anybody knows where to get the door lock knobs that are straight, as opposed to the stock chrome ones, that a kid and a coat hanger can get into the car with? I remember seeing them on other GMs, but I cant remember which models. I also looked in the "Help" section at Autozone with no luck. I didnt want to just unscrew the stock ones, leaving a threaded rod sticking up. TIA