* Underneath the truck: You'll need to get underneath the vehicle to access it. Use jack stands for safety. Never work under a vehicle supported only by a jack.
* Towards the front: The oil pan is generally located towards the front of the engine.
* Center or slightly offset: The drain plug itself will be near the center of the oil pan, but it might be slightly offset to one side or the other.
You'll need to consult a repair manual or look at diagrams specific to your Silverado's engine (4.3L, 4.8L, 5.3L, or 6.0L were common in 2001). These will show the exact location of the drain plug and help you identify it amongst other bolts in the area. A picture search online for "[your engine size] 2001 Chevy Silverado oil drain plug" might also help.
Be extremely careful when locating and removing the drain plug. The oil will be hot if the engine has recently been running. Use a properly sized wrench to avoid stripping the plug.
