Dick asked me to post this link up for him, some pretty good info there...

http://forums.corral.net/forums/classic-mustangs-fords/889814-width-65-68-mustang-8-inch-vs-87-93-8-8-a.html

REAR END HOUSING WIDTHS OF VARIOUS FORD VEHICLES:

Measured from the inside of one axle tube end flange, to the inside of the opposite axle tube end flange --(where the brake backing plates bolt to the ends of the housing, and NOT taken from the wheel-flange-to-wheel-flange distance, --where the back of the wheel would mate up to the face of the drum/disk).

1. 1965-1966 Mustang 8 & 9-inch housing width: 52¼".

2. 1967-1970 Mustang 8 & 9-inch housing width: 54¼".

3. 1971-1973 Mustang 8 & 9-inch housing width: 56".

4. 1957-1959 Ford big-cars 9-inch housing width: 52¼".

5. 1960 model T-Bird 9-inch housing width: 52¾".

6. 1975-1980 Granada/Monarch 8 & 9-inch housing width: 52¼"

7. 1977-1980 Lincoln Versailles 9-inch housing width: 52¼"

8. *1957-1972 Ford pickup 9-inch housing width: 56"

9. 1973-1979 Ford pickup 9-inch housing width: 59¾"

10. 1980-1985 Ford pickup 9-inch housing width:??

11. 1966-1977 Ford Bronco housing width: 52¼"