spare pcm flashing

[superwagon]

I am thinking about picking up another pcm for my suburban. I have unlimited gen III trucks. I am trying to understand what I would need to do to a new pcm before it would work in our rig. Will I need to have it flashed at the dealer before I can write my tune to it? Or could I just write entire my original tune to a new pcm? I am also looking at j2534 options like the mongoose or cardaq etc.

[Montecarlodrag]

If the PCM came from the same year/model vehicle you have license for, you don't need to do anything. Just read stock tune, save it and copy all diferences from your current tune.