Thermostat on 2001 Chevy silverado 5.3 liter engine where is it under the hood?

The thermostat on a 2001 Chevy Silverado 5.3L engine is located on the engine block, at the back of the engine, near the passenger side (right side). It's usually in the lower portion of the engine where the coolant passages meet the engine block.

Because it's tucked back there, it can be a bit difficult to access. You'll likely need to remove some components to get a good look and reach it. A service manual or a detailed online guide with pictures specific to the 2001 5.3L will be very helpful for locating and replacing it.