I have a couple questions for you guys, I know the LMM is the newer body style from 08 up, i also know that the LLY/LBZ is the classic look.

1) what does LMM, LLY, and LBZ stand for?
2) i have an 07 silverado classic witht the duramax, would that be LLY or LBZ?

thanks guys

 

Those RPO codes have nothing to do with the body style. They have to do with which engine is in the truck.

LBZ\LMM = Engine - Diesel, 8 Cyl.,6.6L, DI, V8, Turbo-High, HO, Duramax
LLY = Engine - Diesel, 8 Cyl.,6.6L, DI, V8, Turbo-High, Duramax