* Vortec 6.0L V8: This was the standard engine for the 2500HD. It produced 300 horsepower and 360 lb-ft of torque.
* Vortec 8.1L V8: This was an optional engine for the 2500HD. It produced 340 horsepower and 455 lb-ft of torque.
* Duramax 6.6L Turbo Diesel V8: This was also an optional engine for the 2500HD. It produced 300 horsepower and 520 lb-ft of torque.
To determine the exact engine size for your specific 2003 Silverado 2500HD, you can check the vehicle's VIN (Vehicle Identification Number) or look in the owner's manual.
