the thermostat you mean if so take the upper hose off of the neck at the top of the engine then take the neck off of the engine which exposes the thermostat remove it and stuff a rag in that hole to prevent debris from dropping in the engine while you clean the mating surfaces of the engine (where the neck touches the engine and the bottom of the neck where it touches the engine) now take the rag out carefully (debris) and drop the new thermostat in and put some RTV sealant it could also be called make a gasket it's a high temperature formula and put an eight inch bead around the mating surface, when you do this put the sealant toward the inside of the bolts (a perfect circle) and install the neck then the hose and top the radiator and coolant tank off with fluid. It's also not a bad idea to replace your radiator cap too because of its age and the spring in it has worn down to a lower presure rating and will put tooo much coolant back into the coolant resevoir when it doesnt need to be basically overheating your engine. NOW SIR THATS STEP BY STEP GOOD LUCK TO YOU MY WRISTS HURT NOW AND PLEASE RATE THIS ANSWER THE HIGHEST IT WILL GO BECAUSE THATS HOW TO DO IT AND THATS STEP BY STEP

#1 Raise and support the car on jackstands. #2 Place the drain pan under the transmission fluid pan. #3 Starting at the rear of the pan and working toward the front, loosen the attaching bolts and allow the fluid to drain. Finally remove all of the pan attaching bolts except two at the front, to allow the fluid to further drain. With fluid drained, install two bolts on the rear side of the pan to temporarily hold it in place. #4 Remove the converter drain plug access cover from the lower end of the converter housing. #5 Remove the converter-to-flywheel attaching nuts. Place a wrench on the crankshaft pulley attaching bolt to turn the converter to gain access to the nuts. #6 With the wrench on the crankshaft pulley attaching bolt, turn the converter to gain access to the converter drain plug. Place a drain pan under the converter to catch the fluid and remove the plug. After the fluid has been drained, reinstall the plug. #7 Disconnect the driveshaft from the rear axle and slide shaft rearward from the transmission. Install a seal installation tool in the extension housing to prevent fluid leakage. #8 Disconnect the speedometer cable from the extension housing. #9 Disconnect the downshift and manual linkage rods from the levers at the transmission. #10 Disconnect the oil cooler lines from the transmission. #11 Grab thermistor with pliers, twist and pull.