Ford has records only back to 96'
http://www.motorcraftservice.com/vd...ageid=calibration_pub&gutsid=calibration_menu
More info but still doesn't say specifically what was changed about the fuel injection parameters. If any.
http://www.cb4x4.com/PDFs/Engine - EFI - EEC Program Codes.pdf
At first I though it would be for batch or sequential fire, but I couldn't say at this point.
That being said it IS an emissions calibration code! It may have been done simply because some states testing stations could not read the PCM correctly without a patch. (this is the most likely scenario in my opinion)
You remember those days? the tech would be dig'n around to find the right connector!, and then fail you because his computer failed to connect! Nowadays for OBD-I they don't even connect to it, if the check engine light goes out after start they assume all's well.
From what I can gather it is just a firmware update. Probably to correct a glitch rather than a tuning change. In which case yours has probably been done when it was near new. If so a "tear tag" may have been placed somewhere on the truck, passenger toe kick, PCM itself, door jam, near the brake booster, yata yata... .Of course it would be IF the dealer had the mechanic apply the update sticker in the first place.
I do know that some of these were simply to add more code definitions to the code table and made no other changes to the programming and were simply done before the vehicle was sold via the test port.
This doesn't provide much comfort does it? Only to get worse with time. I bought a PCM a year ago, just in case. The one I got was an Identical part and tune code however. Test ran it and put it back in the static bag for that fatal day... ..
Now that I blew the trans I'm thinking when I finally cook the motor it's 5.0 and OBD-II time. May even do it now. Sell the 4.0 and all the OBD-I stuff to help with the cost.