2003 SILVERADO 2500 6.0 - P0327 P0322 KNOCK SENSOR
Very common issue on these engine, there's two knock sensor. From experience only use AC Delco product and always replace the harness with it. Make sure you torque it down to 15 ft lbs. I would recommend replacing the intake gasket while you're in there. A good knock sensor should show about 93k - 107k ohms of resistance.