Lost your fuel tank cap while on the road? Look no further than 4 State Truck for Peterbilt 389 aftermarket fuel tank caps. We have vented, non-venting, locking and non-locking aftermarket fuel tank caps to ensure you find the perfect one for you and your Peterbilt semi truck's fuel tank. Find the best prices on the best fuel tank parts, like caps, in the business at 4 State Trucks.