Section 05-00: Axle and Driveshaft—Service | 1994 Mustang Workshop Manual |
The Plant Code on the identification tag is to be used as the official service identifier.
The Plant Code for a particular rear axle housing (4010)
assembly will not be duplicated. In addition, the Plant Code
will not change as long as that particular rear axle housing
assembly never undergoes an external
design change. 
If, however, an internal design change takes place
in the same rear axle housing
during the production life of the axle and that internal
change affects service parts, interchangeability, a dash and numerical suffix
will be added to the Plant Code. 
The Vehicle Certification Label (V.C. Label) is affixed on the LH front
door lock panel or door pillar. The V.C. Label contains the rear axle housing
ID code in the lower RH corner. 