Have you ever wondered what kind of engine you're looking at when opening the hood of a Ford? Well, Ford took some steps to make sure their service employees didn't have to guess when working on a car. The 428 CJ and SCJ, for example, were originally identified by a small steel tag that was mounted to the top of the engine under the ignition coil mounting bracket. The bolt that secured the coil bracket also secured the tag.
The tag included information to identify the engine displacement in cubic inches, the two-digit model year, the engine change level, the year and month of production, and an identifying code number. The code number contains three digits and an alphabetic suffix. One challenge to hobbyists has been in figuring out what the different suffixes mean. The 1975 MPC says that "prefixes and suffixes are for Ford Motor Company use only and do not affect engine identification". There do, however, appear to be patterns to their use based on analysis of build (broadcast) sheets. The code on the tag is supposed to match the code found on the build sheet.
A summary of the documented 428 CJ and SCJ engine codes and suffixes appears in the following table.
|Code||Observed Suffixes||Year||Engine Type||Transmission Type|
|420||A, S, T||1969, 1970||Cobra Jet||Manual|
|421||A, AG, B, S, T||1969, 1970||Cobra Jet||Automatic|
|422||1969, 1970||Super Cobra Jet||Manual|
|423||S||1969, 1970||Super Cobra Jet||Automatic|
|424||A, S, T||1969, 1970||Super Cobra Jet||Manual|
|425||A, T||1969, 1970||Super Cobra Jet||Automatic|
|426||1969, 1970||Super Cobra Jet||Manual|
Ford documentation describes the 407, 408, 420, and 421 codes being used on 1968 (407 and 408) and 1969 (420 and 421) Mustangs equipped without air conditioning. In 1970, the 420 and 421 codes were described for use on cars equipped with air conditioning. Exceptions to the documentation have been observed.
Reproduction tags are available from Marti Auto Works. Please contact them directly for details.