I did a segment swap from a 2004 truck O/S 12587603 into a 2004 GTO O/S 12587604. The 'Trans' and 'Trans Diag' segments were identical length in both calibrations. I did the swap using a hex editor in binary. I programmed a PCM and read a file out in a few different formats if anyone can test that might have a ls1 4l80e combo.

zip file contains

binary
tuner cat obd2
efi live v8
hp tuners

all from the same PCM. This is untested, but should work. The rest of the GTO file is STOCK.