2003 Buick Century ENGINE COOLING TEMP SENDER /SENSOR

I GOT A TEMP SENDER AND SENSOR , WENT TO THE HAYNES MANUAL FOR LOCATIONS, THE ONE ABOVE THE THERMOSTAT HOUSING IS CALLED A SENDER ON ONE PAGE AND THEN THEY CALL IT A SENSOR ON ANOTHER PAGE. THEY DON'T SHOW THE LOCATION OF THE OTHER SENSOR/SENDER IN THE BOOK.!! IS THE ONE ABOVE THE THERMOSTAT THE SENDER? I AM DOING THIS BECAUSE OF POOR MILEAGE.