* Vortec 6.0L V8: This was the standard engine, producing 325 horsepower and 385 lb-ft of torque.
* Vortec 8.1L V8: This was an optional engine, producing 340 horsepower and 455 lb-ft of torque.
* Duramax 6.6L V8 Turbo-Diesel: This was also an optional engine, producing 300 horsepower and 520 lb-ft of torque.
It's important to note that the specific engine in your 2005 Silverado 2500HD will depend on its trim level and configuration. You can find out the exact engine size by checking your vehicle's VIN (Vehicle Identification Number) or by looking at the engine itself.
