A transmission/heat exchanger unit includes a transmission having an input and at least one output and a heat exchanger, which is assigned to the output side of the transmission and is connected to said transmission at least indirectly via connecting lines. A duct or ducts route fuel, and is/are integrated in the case of the transmission, and extend(s) at least over part of the axial extent of the case to an end face of the transmission on the output side. A retaining device is provided for fastening the heat exchanger to the end face of the case of the transmission on the output side. The connecting lines that couple the fuel-routing duct or ducts in the transmission with the heat exchanger are integrated in the retaining device. Complementary connections of a standard type and size, which are located on the retaining device and the transmission case, are provided for fuel routing and for fastening the retaining device.