Where the upper rad hose joins the block. Do not be afraid. Pull off everything in sight -- coil, coil bracket, bottom engine shroud (if still in existence), etc. 10 mil, 8 mil, 7 mil, 5 mil, etc. Although I've never seen a bad thermo -- overheating problems are usually the sensor (in the rubber line going back to the heater core), bad relay (Chilton's tell you on this one), locked rad fan, or, blown head gasket resulting in low Aunty Frieze. HINT: boys and girlz, does your temp gauge read cold constantly? SOLUTION: leave the ice road trucking thing to the hillbillies, or, TWO, crimp the female temp sensor wire connector (sensor is in the coolant line which goes to the heater core. This sensor has one wire. There are two sensors here. The other one signals the cooling fan to turn on). Otherwise, you might replace the gauge, or You will waste resources replacing the sending unit for naught, and say bad words. Besides figuring out what naught means. The crimp loosens, and the gauge gets erratic as hell. HINT THREE whenever putting on a wire or connecting two wire harnesses, pull them apart after connection. If they pop off, you are a rookie. If you don't feel some significant resistance (like the temp sensor wire) you will get poor connection. Only a dummy would forget to do this. Like me.