Why is my 1991 ford f250 manual truck overheating?

Hello, transmission operation -- including the master cylinder, slave cylinder, clutch...will not influence engine overheating. Fuel went somewhere -- also not related to overheating -- and really -- unknown based on the information you have shared -- can you even quantify the fuel you feel you lost? Lastly, overheating (what engine do you have?) can occur for several reasons -- do you have a restriction? A leak? Is the radiator getting cooled by air flow -- is there any debris in front of it? Is the fan and fan clutch working? Is your water pump pushing the flow of coolant? Too hard to guess without hands on inspection.