* Ford 9-inch: This is a very popular and likely candidate. Many variations of the 9-inch existed, with different gear ratios available.
* Ford 8-inch: This was also used in some F-100s, particularly lighter-duty versions. Again, gear ratios varied.
To know for sure what rear axle a *specific* 1964 Ford F-100 has, you'd need to:
* Check the vehicle's data plate: This plate often lists axle ratio and may provide clues about the axle type.
* Inspect the differential housing: The housing itself has casting numbers that can be used to identify the axle type. Online resources and Ford parts catalogs can help decipher these numbers.
* Look at the axle itself: The axle shafts and other components can sometimes give clues.
Without more information about the specific truck, it's impossible to say definitively which rear axle it has.