It's the same. An LLY would have a 2 as the 8th digit and an LBZ would have a D. Or you could look at the badges (as long as they haven't been changed), the LBZ would have the Allison emblem on it and say "Allison" and the LLY would not. You can also pop the hood and look on top of the air filter box at the emissions tag. The LLY will state the advertised HP as 310 and the LBZ would be 360.