* Vehicle Identification Number (VIN): The VIN, located on the dashboard and possibly other locations, contains information that can *sometimes* help. While the VIN doesn't explicitly state the engine, decoding it might reveal the original engine *type* (e.g., 273, 383, 440). However, this isn't guaranteed as engine swaps were common. You'll need a Dodge VIN decoder (many are available online) to interpret the information correctly.
* Engine Casting Number: The engine block itself has a casting number. This number is crucial. By looking up this number (usually found on a prominent flat area of the block), you can determine the engine's specifications and potentially the year of manufacture. Compare this information to what the VIN *suggests* was originally installed. A discrepancy strongly suggests an engine swap. You'll need a resource that lists Dodge engine casting numbers and their corresponding years and models. Some online forums dedicated to classic Dodge cars may be helpful for this.
* Matching Numbers: Ideally, the engine block number, the transmission number (if present), and even the carburetor number should all match the original specifications as documented by the VIN. This is the strongest evidence for an original engine. However, even if some numbers match, others might not due to rebuilds or part replacements over the years.
* Engine Bay Condition and Components: A careful inspection of the engine bay can offer clues. Does everything appear to be of the correct era? Are the hoses, wiring, and other components consistent with the car's year and original engine type? Inconsistencies suggest modifications or replacements, which are often signs of an engine swap.
* Documentation: If the car has any original paperwork, such as a build sheet or service records, this would be the most definitive proof. These documents explicitly state the engine that was initially installed.
Important Considerations:
* Partial Matching: Finding some but not all matching numbers doesn't necessarily mean the engine is not original. Components might have been replaced during routine maintenance or repairs.
* Rebuilt Engines: An original engine could have been completely rebuilt, rendering the numbers less meaningful for determining originality. The rebuild could have included replacing some internal components.
* Common Swaps: Certain engines were more common swaps than others, so even if you find inconsistencies, the engine might be a very common replacement for a particular model.
In summary, determining originality requires a combination of research, careful inspection, and a bit of detective work. The engine casting number is the most critical piece of information. Don't rely on just one piece of evidence; consider everything together to form a reasonable conclusion.
