ok i was having a hard time getting a 9 inch rearend for my 1965 falcon i did some work for this guy and he gave me a rearend out of a 1969 rachero so i took a tape mesure to it and it was 52 inches and the cool thing is that i check the four lug on mine and it was the same all i had to do was move the spring perches the 1969 mustang and ranchero are the same so all you have to do is move the perches