His truck was fine for 40 years. Now, suddenly, it must have an electric fuel pump? Bull!
I agree.
To the OP:
Try to verify it is a fuel delivery problem. Mechanical pumps either work or they don't. If they fail, they spray gas out the atmospheric vent hole side of the simple diaphragm body.
Fuel delivery issues with a mechanical pump that does not have a bad diaphragm, points to restriction/blockage upstream of the pump. (between pump and tank or tanks)
Often times there are inline filters between the tank and pump, if those become plugged then the pump will starve. Kinks in hard lines, old soft line pieces at the tank outlet, screen sock on the pickup tube inside the tank on the sending unit.