57=58 ford 9 inch are a bolt in also the 9 inch granada monarch optional 9 inch disc or lincoln versailles fit just get the right factory parts v8 falcons had all diferent parts than the 6 if you have 5 bolt wheels you are in luck also maverick v8 stuff will fit and some 6 mavericks had disk 5 bols set ups also. stay with small block ford it's a lot easier mustang 5.0 after 87 had a narror enough 8.8 rear to fit but were coil springs. you can install the granada, monarch versailles, disc maverick spindles to your falcon parts. the stock v8 falcons had a lot of bump steer when you put your foot in it. Mustang II with biger brakes is a better system and alot of old 65-66 mustang have been changed over.64 mustang sharred a lot of parts witth falcon.