Where is the coolant temperature sensor located?

Ford has two different sensors for coolant temperature for that truck. One sensor that screws into the rear of the left-hand cylinder head close to the firewall and another that screws into the thermostat housing at the front of the engine. They can have either one or both depending on the options on the truck. Attached are the locations for both units. For replacement, the one that screws into the cylinder head doesn't require that you drain the coolant as it screws into a bolt hole in the head, the one that goes into the thermostat housing however does require you to drain the coolant below it. Or you can try the old hose squeeze trick. Namely you break the sensor free, then unscrew it most of the way, then you squeeze the upper radiator hose and release it, at the same time you release the hose you remove the sensor from the last threads and put the replacement in, If you are fast enough you only lose a small amount of coolant.