* Check the alternator itself: The amperage rating is usually stamped directly onto the alternator housing.
* Check your owner's manual: If you have the original owner's manual, it might specify the alternator rating.
* Consult a Ford parts website: Input your vehicle's VIN (Vehicle Identification Number) into a reputable Ford parts website (or a general auto parts website like AutoZone, Advance Auto Parts, etc.). The correct part number for your alternator will reveal its amperage.
Without one of these sources, any answer would be purely speculative.