This is more of a verification that my train of thought is on track.

I am swapping a L67 into a '03 Bonneville SLE. The donor is a '04 Park Ave Ultra. After looking at the wiring diagram of both cars, my original plan was to take the harness with the engine but found the at the fuse block it has a different pinout. (LeSabre would have been the same) So, now I am going to take the harness off the L36 and patch in what's needed from the L67 so It matches or possibly just purchase the harness from Intense so that everything physically connects to the PCM.

I have not unlocked either PCM with HPT yet. I have gone to the tune repository and downloaded the Stock SSEi .HPT file for the 03 year. Can I open it, change the VIN and write all and that change the OS as well? Or does the bin itself need to be changed then verify the VIN? I have looked and have not found it. Possibly I am using the wrong search keywords.

I did find this and leads me to believe that I can change to the L67(SSEi) OS using my PCM.
https://forum.hptuners.com/showthrea...anging-Base-OS