1996-97 PCM "catch code" differences

[allmyEXes]

As I work on and around my 1997 Merc Mountaineer I wonder how long used and reworked PCMs will be available. I have found several that could be the same or near the same as what I have. Keep in mind my MM is an early 1997 2wd auto My code or "catch code" is SLL4. I am seeing used PCMs out there for similar application with codes from SLL!, Sll2, SLL3 and Sll4. What is the difference and will my 5.0 run on any of these coded ones and say for instance is SLL4 an updated version as SLL1. I simply wanting to pick me up a spare PCM for the future.

 

[fwttg]

Check this site: Ford PCM firmware (calibration update) database . It may help you determine if those SLL* numbers are compatible.

There is also a Ford list of PCMs that I came across somewhere but can't locate now.

Several months ago I replaced the PCM on a 1997 Aerostar 3.0l V6 with a remanufactured one. Worked great for a month or two then completely dead. Exchanged it on warranty. Now getting a few errors and won't come out of Open Loop Fault.

Found a wrecker PCM that was listed as compatible but has a slightly different number. According to the link above the wrecker PCM (F79F-12A650-AB, NBZ1) was updated (F79F-12A650-AD, NBZ3).

The Ford list showed the wrecker PCM was for 1996 and the remanufactured for1997. In either case, so far so good and the Aerostar is running. I've got another of the older '1996' PCMs on the way for back up!

I don't know if the remanufactured PCM is bad or if the calibration is that much more specific. Will likely try and exchange it a second time.