• Designed for the L5P Diesel Engine with two tank caps • One cap is located on the side of the tank (Vented) with right-hand threads • The other is located on the top of the tank (Non-Vented) with left-hand threads • This is designed to eliminate any chance of installing the non-vented cap where a vented cap is required • O-rings on the center core seal off the tank vent port for proper testing • Applications: • 2017+ Chevroet Silverado • 2017+ GMC Sierra w/ Duramax