Restore fuel delivery, smooth operation, and dependable performance on your 2004.5-2005 GM 6.6L Duramax LLY with this new genuine Bosch Fuel Injector. This direct-fit common rail injector helps maintain proper OE fuel system function. A worn or failing injector can cause hard starting, rough idle, excessive smoke, fuel knock, reduced power, poor fuel economy, and rail pressure-related drivability concerns. Bosch: 0445120027, 0 445 120 027 Cross References: 0986435504, 0 986 435 504, 97303657, 97780144 Installation Note: Follow proper fuel system cleanliness procedures during installation. Fitment Note: Verify build date, VIN, engine application, and existing part number before ordering.