Mustang 428 Cobra Jet Engine ID Codes

Ever wonder 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 the 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.

This 1968 407J tag was found on an engine with an 8C1 block casting date and an 8D10 engine assembly date.
1969 419T
1969 421T
1970 420A

I've tried to summarize what I know about the documented 428 CJ and SCJ engine code numbers and suffixes in the table below. The information on "Other Options" is a guess based on observations. Additional insights would be helpful. See the footnotes under the table for a description of exceptions and oddities.

Code	Year	Engine Type	Transmission Type	Other Options
407J	1968	Cobra Jet	Automatic	N/A
408J	1968	Cobra Jet	Manual	N/A
419T	1969	Cobra Jet	TBD	N/A
420S	1969	Cobra Jet	Manual	N/A
420T	1969	Cobra Jet	Manual	N/A
421S¹	1969	Cobra Jet	Automatic	without air conditioning
421T²	1969	Cobra Jet	Automatic	with air conditioning
423S³	1969	Super Cobra Jet	Automatic	N/A
424S	1969	Super Cobra Jet	Manual	N/A
424T	1969	Super Cobra Jet	Manual	N/A
425T	1969	Super Cobra Jet	Automatic	N/A
420A	1970	Cobra Jet	Manual	N/A
421A	1970	Cobra Jet	Automatic	N/A
421AG	1970	Cobra Jet	Automatic	with air conditioning
421B	1970	Cobra Jet	Automatic	without air conditioning
424A	1970	Super Cobra Jet	Manual	N/A

1: I have multiple build sheets that do not list air conditioning with this engine code, but I also have one that lists air conditioning.

2: I have multiple build sheets that list air conditioning with this engine code, but I also have one that doesn't list air conditioning.

3: The one build sheet I have with this code looks like a reproduction, so I'm not sure about the data.

Please note that I've only described codes that I've seen listed on build sheets. Ford documentation also describes a CJ code 418 (also seen on an engine tag from a 1969 V-code SCJ Torino with engine code 418T) and SCJ codes 422 and 426. Do you have any information describing these or any of the codes listed above? Please consider sharing what you have to make the table more complete.

Reproduction tags are available from Marti Auto Works. Please contact them directly for details.