Whether you’re building a custom rig or working on a new render, this should save you some serious time. Check out the GMC Heritage Center for official specs if you're aiming for 100% accuracy.
Use this if you are sharing a 3D model, a mod for a game, or a collection of reference photos. Download File 132 - GMC-Truck.zip
Since the intent is slightly ambiguous, Choice 1: The Community Resource Post (Most Likely) Whether you’re building a custom rig or working
You are looking for a specific file that you can't find. a mod for a game
You want to explain how to use the contents of that specific zip file (e.g., how to install a truck mod).