How do you correctly install a thermostat on a 94 ford ranger?

Answer 1

Should be located in a removable housing at the engine end of the upper radiator hose Drain about 1 gallon of coolant from the radiator

Remove this housing

Note how thermostat is installed

Clean both surfaces

Replace thermostat and gasket

Re-install housing

Re-fill coolant slowly to prevent an air lock

Start engine and look for leaks

Run engine to normal operating temperature with heater on

Re-check coolant level