If you are referring to the top grease fitting on each of the king pins, they can be reached using a flexible grease gun hose and by turning the steering wheel to provide better accessibility. They are #1 and #2 on the attached drawing. The other difficult to locate grease fitting is on the steering gearbox (#9 on the drawing). This grease fitting is covered with a small plastic cap, so it can be tough to see. It can be reached by opening the front hood cover.
Harbor Freight sells an inexpensive hose that I use with a grease gun for the Ford chassis: 9 in. Grease Gun Hose
Valvoline makes a grease that contains molybdenum and meets Ford's specifications. It's available at Advance Auto Parts stores.