2004 - 2005 6.6L Duramax LLY

The 6.6L Duramax LLY was introduced in the middle of 2004 and was produced through early 2006.

Considering that it came out in the middle of 2004, it’s possible to have a GM truck from that period with either the LLY or the previous LB7. If you’re not sure which one you have, you can check the 8th digit of your truck’s VIN to find out. If the 8th digit of your truck’s VIN is a 2, then you have the Duramax LLY.

Most versions of the LLY Duramax produced 310 horsepower at 3000 RPM and 520 pound-feet of torque at 1600 rpm. The early 2006 models produced 605 pound-feet of torque at 1600 rpm.