The invention relates to a transmission module, especially a transmission module in countershaft design, having at least one input and one output which are connected with each other by way of at least one speed-torque converter device, with a reverse gear which is arranged between a countershaft and the transmission output, with a hydrodynamic retarder. The hydrodynamic retarder having at least one rotor blade wheel and a stator. The rotor blade wheel is connected via a high gear with the transmission output. The high gear is a component of the reverse gear.