Where is the thermostat located on a 1996 Ford Ranger 4 cylinder?

The thermostat on a 1996 Ford Ranger 4-cylinder engine is located at the back of the engine, on the intake manifold. It's usually tucked in a somewhat difficult-to-reach spot. You'll likely need to remove some hoses and possibly other components to access it. A repair manual specific to your year and engine (check for displacement, e.g., 2.3L) will provide the most accurate location and detailed instructions.