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.

The Duramax 6.6-liter turbocharged diesel engine is radically upgraded for 2006. On available GMC Sierra models, an LBZ version of the 6.6-liter Duramax diesel is offered with a 650 pound-feet of ...