2013 6L80 Transmission swap ECM Flash?
 

I will be swapping out the transmission, as the fluid is completely burned and the torque converter shutters / slipping at low RPMs when locked up.
I hear the ECM will need to be re-flashed after the transmission is swapped.
1 - Is this a true statement?
2 - If so, what does the re-flash do?
3 - Can the truck be driven to the dealer to get flashed?

Just swap the TCM inside the transmission. You will have to pull the pan and maybe drop the valve body…