Two new ten-speed transmission models have been developed to serve the latest trends in the on-highway heavy duty truck market. These new transmissions combine the Eaton® Fuller® Twin Countershaft design with unique features that improve driver ease and transmission performance.Both models are rated with a torque capacity of 1450 lb-ft (200 kgm). One model is an overdrive transmission having a model designation of RTLO-14610A. The second is a direct and overdrive version having model designations of RT-14710B and RTX-14710B. In this paper, this model is identified as the RT/RTX-14710B.