Where is the thermostat located on a 1996 Chevy lumina 3.1 engine?

On a 1996 Chevy Lumina with a 3.1-liter engine, the thermostat is located at the engine end of the upper radiator hose. To access it, you'll need to disconnect the upper radiator hose from the thermostat housing, which is bolted to the engine. The thermostat itself sits inside the housing, where it regulates coolant flow between the engine and the radiator.