The most noticeable difference is the revised emissions components. You can see in the graphic below the Diesel Oxidation Catalyst, DOC, has been moved closer to the turbocharger for improved efficiency. This is a simple way to tell the difference, you can just pop the hood and look at the turbocharger.
The second way to tell the difference is by simply looking at the Vehicle Identification Number, VIN, the 8th digit in the VIN will tell you what engine option your truck is outfitted with. If the 8th digit is a "T" that means its and LM2, if the 8th digit is a "8" then you will know that your truck is outfitted with and LZ0.
It is helpful to understand your VIN for your own information, the first 3 digits are the World Manufacturer Identifier, otherwise known as the WMI and will identify where your vehicle was made. If the first digit is a 3, then it was made in Mexico, if it is a 1 then it was made in the US. The next 6 digits are the Vehicle Descriptor Section, VDS, it is used to specify the type of vehicle and may include information about the model, platform, engine and transmission. The final 8 digits are the Vehicle Identification Section or VIS.
