I sent mike my modded 03 os if anyone wants it pm me your email addy u will forward it. Its set for 3600rpm shifts with slip limit raised.
The EARLY 01 OS and the early 02 OS had problems with the 2-1 downshift. If you run the updated 01 OS from GM, it does not suffer from this problem. Also the 01-02 OS's can have OD lockout, but it isn't done through the tow haul button like 03-05 trucks were, it was through a hard wired switch to the TCM.Ill stick with the 03 os in my 05. I think it has the best shifts personally. The 01 os always has a harsh 2-1 downshift in my lly (as well as my lb7) , can't modify slip inhibit tables, and lose my high idle.