I noticed that a long time ago. From my observations, 4-lugs are normally used on small, 4-6 cylinder cars (Take note one day and see which brand and types of cars have 4 and 5 lug wheels) so I found it unusual when I saw that the Fox body Mustang was at the time, the only V8-equiped car with 4-lug wheels.
It's the chassis that makes the difference. The Fox chassis actually got it beginnings in 1978 as a Fairmont. Although a V-8 was available it was rather underpowered and by no means needed a 5 lug axle. You would probably have to get into some pretty serious horsepower and torque before you could shear the lug studs off.
i just put the front on to see how the look.i bought them off a guy on here with good front tires and shot rears.i bought them used at a good price so i couldnt tell you what the are new.