Seems that all of the trucks have this. Mine came with block off caps but they had cracked and fell off. The TSB for the severe duty filtration kit has a part number for the tank vent kit. It's about $80. I used a length of 1/4 in hose and made a "T" fitting and tied it in to the fuel tank vent, NO MORE FUEL LEAK AND WATER. Was the cheapest way to go.