Show where the thermostat is located on a 2000 Chevrolet Impala LS?

The thermostat on a 2000 Chevrolet Impala LS is located on the engine, underneath the intake manifold. It's not easily accessible without some mechanical work. You'll likely need to remove parts of the intake manifold to get to it. It's a job best left to a mechanic unless you have significant experience working on engines. There's no easily visible external location like in some vehicles.