The full AC clutch is difficult to change on the car. The field coil is very difficult to change on the car. If an aftermarket clutch is used, the entrie clutch has to be swapped including the field coil.
If you use a name brand Ford clutch, it is possible to swap everything BUT the field coil. Reuse the old field coil. Recommend getting a real set of snap ring pliers. Otherwise it will be a real lesson in frustration.