The Duramax was introduced in 2001 in the GMC and Chevy heavy duty pickups. The first version of the engine was code named LB7. This version was produced from 2001-2004. It can be identified by the 8th digit of the VIN number which should be a 1.
This engine was a great performer but originally suffered from a lot of injector issues. The original injector design would fail and cause hard starts, smoke at idle, and fuel dillution in the oil. The later versions of replacement injectors fixed this issue.