This is a list that was compiled by some fine folks on the MercuryCougar.net website. I take no credit for it but I didn't want to see it slip away into obscurity. Some of the listings are a little redundant but I will try and clean it up as I can.

Year & Model Axle Length Notes 
1965-1966 Mustang 57.25 inches 
1967-1970 Mustang 59.25 inches 
1971-1973 Mustang 61.25 inches 
1977-1981 Versailles 58.50 inches 
1967-1973 Mustang, Torino, Ranchero, Fairlane 59.25 inches to 
61.25 inches 
1957-1959 Ranchero and station wagon 57.25 inches 
1966-1977 Bronco 58 inches 
1977-1981 Granada/Versailles 58 inches 
1967-1971 Comet, Cougar, Mustang, Fairlane 59.25 inches 
1971-1973 Mustang 61.25 inches 
1964 Falcon 58 inches 
1967 Cougar 60 inches 
1967 Fairlane 63.50 inches coil springs 
1972 Ford Van 3/4 ton 68 inches 
1973-1986 Ford Van 3/4 ton 65.25 inches 
1957-1959 Ranchero and station wagon 
57.25 inches 
narrowest 9" housing 
1966-1977 Bronco 58 inches 5-on-5 1/2 inch diameter bolt circle 
1967-1973 Torinos, Rancheros, Fairlanes 59.25 inches or 
61.25 inches 
1967-1971 Comets, Cougars, Fairlanes 59.25 inches 
1975 Mustang II 8" 57.00 inches 
1974 Maverick 8" 56.50 inches