Your Duster should have numbers stamped on the radiator support, usually anywhere from the center to the left (drivers side) and it can either be on the top of the support, or on the side where it would be hard to see. It's typically under the antifreeze sticker. Your car should also have numbers stamped in the rear, and on Dusters it will be visible from inside the trunk. Look on the bottom of the package tray, drivers side, near the speaker hole.