A new series of truck transmission has been developed with the intent of customizing the ratios to the engine and the job. Two years of laboratory and field testing has been completed on these transmissions, proving their reliability and performance. This paper covers the development of a new series of heavy duty truck transmissions utilizing the split torque concept of power flow. A chronicle of the development is set forth, as well as an assessment of the most salient features of this series of transmissions. A statement of the present status of the transmission series also is presented.