9 inch rear for 66

[rwoerz]

The rear end out of a 1959 full size Ford (1957 may be the same) is the same width as the 1965/66 Mustang. Overall and spring pad width is the same and the brakes bolt right up. The difference comes with the fact that the older housings axles tubes do not neck down on the ends like the Mustangs and the spring pads are narrower (the leaf spring on the 59 were not as wide). Just make sure that you get the U bolts and the part that the U bolts and the shock attaches to. I used this trick on my 1965 Falcon which has the same read end as the Mustang.