* 5.4L V8: This was the standard engine, producing 300 horsepower and 355 lb-ft of torque.
* 6.8L V10: This was an optional engine, providing more power with 310 horsepower and 425 lb-ft of torque.
It's important to note that these are the factory-installed engine options. If the Navigator has been modified, it may have a different engine. To know for sure what engine is in a specific 2003 Navigator, you would need to check the vehicle's identification number (VIN) or consult the vehicle's documentation.
