How Do I Identify 9 Ford Housings?
The Ford 9-inch differential is a popular vehicle rear end noted for its strength and versatility. Many custom vehicle builders and auto restorers use the Ford 9-inch differential as a replacement, even if the vehicle is not a Ford product. The strength of the housing depends on the variation, making proper identification important when purchasing a used differential, or determining if your vehicle is equipped with a Ford 9-inch differential. The FordMuscle website divides 9-inch housing units into three categories: standard case, war case and "N" case.
Instructions
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Determine if the differential is a Ford 9-inch. Classic Concepts in Ridgecrest, Calif. suggests trying to placing a socket wrench with an extension on one of the axle-side bottom bolts of the differential housing. If the socket cannot be used without hitting the housing, it is a Ford 9-inch. On 8-inch differentials, the extension bar will not hit the housing, allowing for easy bolt extraction. A wrench must be used on the 9-inch housing.
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Look at the differential housing. According to FordMuscle, the rear hump on a 9-inch housing, viewed from the rear of the vehicle, is generally round in appearance. This, along with the previous step, provides basic unit identification.
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Look for visual clues to determine which version of a 9-inch housing is present. On the axle side of the housing, notice any casting particulars. According to FordMuscle, if there is a ribbed pattern, look for a raised letter "N" in a field between the rectangular ribs; this identifies it as an "N" housing. If the rib pattern is present with no "N," it is a war housing. Those with a less defined rib pattern are standard cases.
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Locate the identification tag on the axle side of the housing, if present. If it is, locate the Ford part number. FordMuscle lists standard housing part numbers as C7AE-E, C1AW-4025-C and C4Aw-4025-A, with 4025 being the Ford part number designation for differentials. The prefix portion, C7AE, identifies date of manufacture and original model car installation.
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Tips & Warnings
FordMuscle identifies the best model differential housings as the "N" housings, followed by standard and then war models.