How do I replace thermostat and thermostat housing

Gilbert, not sure which engine you have. As with most water-cooled vehicles, it's between the engine outlet and the radiator inlet. Exact location varies depending on the engine, which you forgot to tell us about. Just follow the top radiator hose toward the engine. Once you find were it connects to the engine, there will be two bolts holding the thermostat housing to the block. Undo those bolts and you should find your thermostat.Make sure you use a new gasket and put the thermostat in there straight. Always be careful when putting the bolts back in the holes, make sure they thread easy so you don't cross thread. Make sure that you clean all old gasket material of the housing and the block. Top off your coolant once you are done. Make sure that you work on your coolant system when the engine is cold. Never try to do this on a hot engine. Hope this helps, good luck.