Where is the radiator petcock on a 2004 silverado 5300 v8?

The 2004 Silverado 1500 (5300 V8 refers to the engine displacement) doesn't have a radiator petcock in the traditional sense like older vehicles. Instead, it uses a drain plug located at the bottom of the radiator. You'll find it on the lower radiator hose connection, usually on the driver's side (left side) of the vehicle. It's typically a plastic cap or a small bolt. You'll need a wrench or pliers to remove it, depending on the type of plug.