* Look for the engine code cast into the block. This is usually located on the side of the engine block, near the front. The code will be a letter/number combination. A 5.2L will have a different code than a 5.9L. Unfortunately, there isn't a single universally understood code - you'll need to cross-reference this code with a Dodge engine code chart (easily found online through a search like "Dodge engine code chart").
* Look at the air cleaner assembly. The size and shape of the air cleaner housing might offer a visual clue, but this is less reliable than checking the engine block.
* Check your vehicle's documentation. Your owner's manual or any other paperwork that came with the truck should specify the engine size.
* Check the vehicle identification number (VIN). The VIN contains information about the vehicle's specifications, including the engine. You can decode the VIN online using various VIN decoder services. This is a less direct method but can be useful if the other methods are inconclusive.
The 5.9L is significantly larger physically than the 5.2L, so a visual comparison might give you a clue, but it's not a reliable method for certain identification. Always rely on the engine block casting code or the vehicle documentation for confirmation.
