How do I know what Ford 9 inch rear end I have?

The middle number is the ring gear diameter in inches, typically an 8 or 9. The last set of numbers is the vehicle plant code. If the axle tag is missing, as most are, you need to remove the third member in order to know what ratio you have and if it has a limited-slip or not.

How do I know if my spline is 28 or 31?

A 28 spline axle will have a recess in the middle while a 31 spline axle will be solid with just a centering champher (from when it was machined and ground at the factory).

How do I identify my Ford rear end?

Locate the identification tag on Ford manufactured rear end units. According to, the tag is located on the driver’s side of the unit, mounted vertically, facing the front of the vehicle.

What vehicles have a Ford 9 inch rear end?

Common applications

  • 1957-1986 Ford F-100 & F-150.
  • 1958-1960 Edsel (All series including Wagons)
  • 1976-1980 Ford Granada.
  • 1976-1979 Lincoln Versallies.
  • 1957-1970 Ford Fairlane.
  • 1957-1971 Ford Thunderbird.
  • 1964 1/2-1973 Ford Mustang.
  • 1966-1983 Ford Bronco.

How do I identify my differential?

Visual Differential Identification Without an ID tag, differentials are identified by the number of cover bolts, the distinctive shape of the cover, the number of ring gear bolts, and ring gear diameter. They can also be identified by whether the center section is an integral or dropout design.

What rear end do I have by VIN?

Identify the VDS section, the fourth through eighth digits of the VIN. This section typically includes information such as the vehicle model, engine size and body type. While not every vehicle manufacturer includes gearbox ratio information in the VDS, this will be where the information is found if it was included.

How do you find out what Differential I have?