I personally have never had any luck with aftermarket or even FORD service part springs as FORD in the later years superseded several part #s and condensed the amount of springs serviced. The problem I have found with replacement springs is the car sits too high. Springs are very specific to a car as engine, transmission and options all effect the ride height. I would recommend either finding a used set or maybe someone who has used a set of aftermarket springs that did work right on a similar optioned car. Be carefull of the vendors as they promise it will be a perfect replacement and will warranty the part if not satisfied however your the one that has to compress that spring and install it which is not one of the funnest parts of working on a mustang or cougar. Another suggestion if you are going to replace the front springs yourself, I have found the best tool is a internal spring compressor that has 4 fingers that compress the spring from the inside, I have never had any luck with the ones that compress inside the shock tower as shown in the service manual.
