if the vehicle is not charging, and the alternator and battery are good, you might want to try replacing the voltage regulator, or having it tested at a parts store. On older Ford products it was typically mounted on one of the fenders under the hood. It looks like a square metal box about 3 x 3 inches, with a flat electrical plug containing 4 wires. Regulator failures are very common on that type of charging system.
If this is helpful, please click my accept button.... thanks!