While the second LLY iteration of the Duramax was a step up, the third generation LBZ Duramax — released in 2006 — was the engine that put the Duramax ahead of the competition. In many ways ...

The mid-2000s was a period of rapid iteration for GM's Duramax engine. The LLY only lasted a couple of years before GM debuted an updated version of the 6.6-liter diesel with a new code name, LBZ.