I really don't get what Mustang5l5 is talking about. Especially when all fox chassis parts are interchangable. That means 78-04(not just mustangs) model years.
What i am getting at is that 87-93 Mustangs are for the most part mechanically superior to 79-86 Mustangs. Doesn't matter if the parts are interchangable...someone still needs to change it.
Who really wants single exhaust, 9" or 10" front brakes, a 7.5" rear, no quad shocks, open differential, 4-spds, 10" clutches, LCA's with mushy oval bushings, non roller block motors, CFI, E6 heads, smaller front fenders, primitive strut tower geometry, etc etc etc.....
I'm pretty sure most 4-eye owners out there upgrade some or all of these parts eventually. But why buy and install when you can buy an 87+ and have it already?