custom operating system for 2002 avalanch 12216125 ecm

[69camaro5speed]

does anyone know what i can flash my ecm with to run custom operating system there isnt one listed on my list for that one i like to run some sd to try a gas milage tune up or can i just change some settings with the stock operating system and do it that way figures the one i want to test with (my avalanch) i cant get a operating system that matches i have a lc1 with the air fuel gauge so i can watch it when driving to make sure i dont damage it thanks in advance for any ideas

[ringram]

You can run sd and open loop with a stock OS. You just dont have dual spark map or a fully commanded afr table (well you can use map vs ect vs afr) B3605 - OLFA table. Probably use a combination of that and normal PE mode and you should be good to go if there is no custom os.
Afterall HSV did something similar with the 300kw tune, though thats closed loop, but SD. Take a look at that tune for some info on how it works.