* Check the VIN: Your vehicle identification number (VIN) contains a code that specifies the engine. You can usually find the VIN on the driver's side dashboard, visible through the windshield. You can then use a VIN decoder (many are available online) to determine the engine.
* Look at the engine itself: The engine block will have a casting number. This number can be used to identify the engine, but finding it might require some effort as it's often located in less accessible areas. You'll need to consult a GM parts catalog or an online database to match the casting number to the engine type.
* Check your owner's manual: Your owner's manual should specify the engine type.
* Look at the glove box sticker: Some vehicles have a sticker in the glove box that lists specifications, including the engine type.
* Check the emissions sticker: Located under the hood, this sticker might contain engine information.
For a 2006 Duramax, you're likely to have one of the following LBZ (6.6L) or LLY (6.6L) engines. However, using the methods above is the only reliable way to confirm.
