1982 Ford F-150

First things first, drain the cooling system and flush it out. Whiile the fluid is out is a good time to replace the thermostat.

After that refill and run it again, still overheating? Check fan shroud and fan for proper function, if thats good pinch the upper hose of the radiator with engine running and thermostat opened after vehicle is hot. You should feel pressure build, when released you should feel water rush by if nothing suspect a faulty water pump.