Would GTA fastback codes be at all helpful?
The car was my daily driver in the 1990s and is now owned by my son. It is a 7R02A149xxx GTA Fastback (w/GT equipment group),...
...It makes me want to run a Marti on this car!
http://www.concoursmustang.com/forum/index.php?topic=16751.15
Assuming the fastback GTA you mention is the same car you speak of in the other thread (on dual exhaust), it is a bit later build...quite possibly using different -suffix codes than my example would have come with. Regardless, fitment/function-wise, they would be the same. Concours-wise, not as likely given the investigation and findings we have done to this date (Feb. 2018). I believe the date stampings combined with the suffix's of such original examples are the key.
In any event, as Jeff mentioned, it would be helpful to get the date code and suffix codes from those springs. Even better if you had the Marti report to add actual build date to perhaps only a scheduled build date (using data plate and/or vin# as our only clue of the car's date).
For reference only in this comment, consecutive number of my build is mid-127XXX (earlier than the 149XXX I assume is your son's car)
On a seperate thought, I seriously wonder (speculate) if the running changes mentioned in the MPC's (shown earlier within this thread), had anything to do with the tire clearance issue they were having with the Wide Oval tires. Just spit-balling an answer as to "why a running change" on the springs.