This tip has been beaten to death on the forums, but it is still a fundamental concept of Fordology. The question is whether a car has an 8-inch or 9-inch Ford. An identification might be needed while looking for a donor rear in a salvage yard, or trying to find out what is in one’s own car. Some 8″ housings look like the early “smoothy” 9-inch housings, so merely peering under a crusty undercarriage will hinder a correct I.D. The centersections of early 8-inch rearends with the single rib look like the later non “N” case 9-inch centersections. Further complicating things is the fact that the early ’57-early 60’s centersections with the two reinforcing ribs look like the later 8-inch centersections. There is an easy I.D. though, read on.

The early Ford 9-inch centersection(left) with two ribs looks suprisingly similar to the later two rib 8-inch centersections. There are also single rib 8-inch and 9-inch centers that look alot alike. Staring at one under a car will not be an easy I.D.

A short 9/16″ socket on a 3/8″ ratchet WILL NOT be able to fully access the two lower retaining nuts on a 9-inch case. The case is too large and will interfere with removing the two lower nuts.

On the other hand, a short 9/16″ socket on a 3/8″ ratchet will fully engage the two lower retaining nuts on an 8-inch case and removal will be possible.

The only way to remove the two lower retaining nuts on a 9-inch centersection is with a box or open-ended 9/16″ wrench.

For more information or questions about this Quick Tech Tip please contact Tom Zuloaga.