Where is a vacuum line on 2003 Chevy Silverado 2500HD?

Well, honey, the vacuum line on a 2003 Chevy Silverado 2500HD is typically located near the intake manifold or throttle body. You might want to grab a flashlight and get down and dirty under the hood to track it down. And remember, if in doubt, consult your vehicle's manual or a professional mechanic before you start yanking things apart.