I am thinking about buying a 2006 (real clean truck). I am getting back to the 06 lly vs. 06 lbz discussion, what the hell is going on here. When I first got interested in this truck, I just assumed that it had the LBZ because it had the Allison select-shift 6-speed transmission in it which is the newer unit. After running the VIN it looks like the 8th digit is a 2 which indicates that this engine is a LLY. I'm not really concerned about the tune because any Bully Dog/Banks/EFI Live can up the H.P., what I am concerned about are the engine internals. It sounds like the LBZ got some nice upgrades compared to the older LLY's (like reduced compression and stronger lower end), but after studying this troubling question, it looks like the 2006 LLY is the same as the 2006 LBZ from a hardware standpoint, it's just that the LBZ powertrain has a more updated tune (probably due to the fact that the other tune was not ready for release until the end of 2006). Does anyone know the real story here? Also, if this story is true, does anyone know how to flash the ecm with the LBZ tune? Any help would be appreciated.