Guessing that the 06 TCM is different than the rest of the 6 speed TCM's? I always figured that if you had a type of TCM (5 spd or 6 spd), you could, with EFILive reprogram it for a 8.1, or Duramax. If that were the case, then all you would need is the rare 8.1L Allison TCM operating system.