Ford Differentials. Joseph Palazzolo

fair amount of detailed information contained within the part number for Ford components.

      The differential is identified by a basic part number, but you may find an engineering part number, which is usually part of the casting, and a service part number, which is found on the parts box or found in the dealer parts system. Regardless whether it is the service part number or the engineering part number, the basic number remains the same. Keep in mind that sometimes an engineering part number was placed on the casting of a part that was used on a different vehicle. So, proceed with caution with this information because it only serves as a basic indicator.

      The basic part number is a series of numbers systematically developed to further divide the vehicle into sub-systems. In fact, sub-assemblies or accessory kits often had a letter in the second position of the basic number. For example, the base number for shift level is 7213 while the indicator for the shift level is 7A213. The C-washers for axle retention are 4N237, axle brackets are 4A263, and even the differential bearing shims are 4A451.

      Another set of basic numbers is reserved for body components and yet another set for service tools, but we are focused on the axle and driveshaft for the purposes of this book.

      The last sequence of numbers or suffix provides revision control for the Design Engineer. Typically, the first revision was given the suffix A and then sequenced to B and so on as design revisions were made. The design revisions were typically very minor, and the parts were interchangeable but of course, you wanted the latest revision. If there were significant changes, the entire part number was updated. But there are exceptions to this as well. For example, the A revision could be an intake manifold for a 2-barrel carburetor, while the B revision could be the 4-barrel carburetor version of the same engine manifold.