Well, the OS do not match. I took the 2002 5.3 Silverado tune from TFD and copied in the 2002 Camaro Trans segment info. They are both the 12212156 OS. My 2001 5.3 that I am actually working with is 12212156 (looks like it was only used in 2001 Silverado???). I have the commercial Scan&Tune so I should be able to flash the new OS on to the PCM, right? The icon is grayed out in my tuning software so I can't. Am I missing something?