Creating XDF for 12579405 O/S 2003 model year.

Ok so I have been told that the XDF file for 12579405 does not exist. There are options as far as using a compare bin or using a 2004 model year O/S but there are complications with that, all I am wanting is an option for complete customer satisfaction with the functionality of a specific year vehicle. So a few different PCM's I have used on my 2003 Z71 with 345k miles and results. First off the truck was sitting for a while I bought it with the transmission completely destroyed, the low reverse planetary had been grenaded so I built another, "different" transmission for it which is also a 4l65e. So this truck once I finally found a corroded broken ground wire at the 3 set on the bell housing bolt and repaired the truck started and ran. The truck rolled coal like a pulling tractor, absolutely preposterous how black the exhaust smoked on this truck. So I put in a different ECM that I flashed with an 04 O/S would not start, Got another PCM on trade that was flashed with deleted s2's ran but still smoked "the battery light came on and the fuel gauge ran backwards ish .. still had CEL codes" so I changed the 02 sensors b1 b2 s1's and it ran like a champ put my ECM from the ls 940 that was still programmed for a 4l60 and it would not start. So.. I put the original ECM back in and it ran like a champ I drove it 40 miles before a check engine light came on. Gas gauge works right no battery light, scanned it while I was fueling up and it showed 11 codes 02, misfire, 02 voltage so i cleared the codes. If i wanted to tune this PCM and keep everything working properly or clone this PCM screwed without an XDF file. If I create the XDF file would that help anyone?

If you have the expertise and knowledge to create a reliable .xdf file for the 9405 operating system, I am more then sure it would be a benefit to some.
I was lucky and my '04 already uses the best developed P59 OS in the 7603.
I did have a ECM/PCM that had the 9405, in fact had two, but they have both been converted to 7603's.

We see request nearly weekly in the various forums and social media pages of individuals with the 9405.
I am not a programmer by any means, but know how to turn the hard parts. So far this educational journey has been fun, and looking forward to my continued knowledge base.