Been reading through the tutorial guides and about 1000 threads about upgrading OS and for the life of me can not figure this out. I have an LS1B OS 12587811 and see the custom OS files in my documents which show 0125001-3 then 0127, 0129, 0201 and so on but how do I know which is the correct one to use? I figured out the 001-3 at the end are the different options within the COS but can not figure out which is the file I would use. Under V7.5, Upgrade OS there is nothing listed so I'm guessing it would show in this box after you flash in the COS file but there again I have to ask which file to load? What is the guru secret to knowing what COS is for what?