The clutch on the front isn't necessary unless your needing all 200 amps. The explanation I found through Alldata:
"when the engine is driving an alternator at a given speed and the automobile's transmission is in a given gear. If the transmission upshifts to a higher gear, the engine speed decreases abruptly. As a result, the V-belt driving the alternator abruptly decreases in speed as well. However, typical alternator rotors have considerable rotational inertia, which opposes the V-belt's abrupt decrease in speed. As a result, the alternator actually attempts to drive the V-belt. However, the interface between the V-belt and the sheave frequently cannot carry the resultant torque, which can be quite large. As a result, the V-belt may slip on the sheave, causing an audible and annoying squeal. An overrunning clutch, which would prevent the alternator from attempting to drive the V-belt in the manner just described, would prevent the squeal."
Here is my thought, your not running all the electrical items needed for 200 amps. In my years of automotive service, unless the belt has significant age to it belt squeal is typically not an issue. The only thing you'll notice going back in amp rating is case size. Ford usually has an alternator case size of 5 1/4 on the lower amperage alternators and 5 5/8 on the high amperage case. My recommendation is for the sake of saving money is find an older alternator from a 99 ford e350 with Ambulance package which will have the high amperage and bigger case but a standard pulley. OR go with the lower amperage alternator. Hope this helps.
1999 Ford Crown Victoria Police Interceptor