Plan on doing the thermostat while you are in their too. Drain the coolant, remove the upper radiator hose from the t/stat housing, remove the upper t/stat housing from the head, remove the t/stat, remove the temp sender. Replace all of the parts with new stuff, refit the housing and hose, refill with coolant, pressure test and look for leaks, fire up and bring to operating temp, recheck for leaks and coolant level. Done

Mark