I'm new here and new to tuning, but I'm going to ask anyway. I have a 2007.5 6.7 Cummins that is already tuned and running well with a single tune. I was interested in keeping that tune. I don't want to write over it. Its my understanding that the only way to save this file would be to swap ecms. I was planning on reading the current file, reading the file off the donor ecm, and then building the new file for the donor ecm. Does this logic sound reasonable? Do I need to read with flashScan or Autocal? Will any cm2100a work that comes from a similar (2007.5-2009) truck. Should the donor ecm be from an automatic with the same trim or does it matter? Thanks for any input.