04 05, doesn't seem to matter once you tune them. With 03-05 you MUST match up the vehicles options as best as possible right down to power windows, locks, push button or floor shift 4x4, radio, ac, ALL of it. They're VERY picky. I'm on my phone so I can't look rough what I have. I would look on autotrader or ebay and find an lly equipped identical to yours, get the vin, look it up on tis2web, and then find a matching tune to it.
Thefermanator i found my exact truck on autotrader with vin 1GCHK23215F926661 and it looks like the OS it has is 15228758. How does someone get a hold of the right OS and calibration. With the operating system i have now the hvac controls dont work right and a couple other things are acting up.