Alright, so I have done the physical swap and now I am into the tuning. Since I changed the engine size, transmission, driveshaft, etc. I am just going to retune from the beginning.

I currently have a 12212156 OS on my PCM (this was upgraded as I have a 2000 Silverado). My question is, can I just download a stock 12212156 OS file and start tuning from the beginning?

The reason I asked this in the transmission section, is I wanted to know if this would keep me from having to do a segment swap for the 60E to 80E upgrade. I would just need to do a FULL flash and not just calibration flash.

The second question is that I downloaded a 12212156 OS that has 4WD. Would this affect the truck at all if I don't have 4WD or does it just ignore the 4WD parameters?

I couldn't find a 2WD 4L80E tune in that OS.