The "REV 1.2" is not the ECM version number. I think it is the display software. The "Calibration", as Navistar calls it, should be "PBL6XWR3 RPLBAG1". The only way for an owner to find out is to call a dealer and have them look it up OR you can purchase a OnCommand Link device and do it all yourself.
2012 Monaco Knight 36 PFT
2019 Jeep Grand Cherokee Overland
2005 Jeep Rubicon Unlimited on 2007 16' Car Hauler trailer.