The 2nd generation of the Duramax Diesel engine was introduced half way through 2004. This generation was named the LLY and lasted from 2004.5 to 2005. It can be identified by the 8th digit of the vehicles VIN which should be 2.
The injectors were upgraded from the previous LB7 version and are now serviceable without removing the valve covers. An EGR emmisions system was introduced as well. Horsepower was rated at 310 at 3,000 rpm.