Each Dayco kit includes all the necessary components to ensure the belt drive system performs optimally – most importantly, its ability to handle higher torque and power pulses. Each kit includes one (1) premium tensioner – either the original flat spring tensioner or the new 2-piece tensioner, two (2) heavy-duty dual bearing pulleys, and one or two (1 or 2) diesel-grade belts treated to increase flexibility, reduce rib cracking, and to run cooler. This kit is for 2003-2020 International, Kenworth, and Volvo models 5500i, 5600i, 9900i, 9900ix, LoneStar, LT625, ProStar, T800, VNL, VNL 300, VNL 400, VNL 740, VNL 760, VNL 860, and VT.