A pump housing containing an inlet and an outlet and enclosing two meshing pumping gear wheels is connected through an intermediate bearing plate to a transmission housing comprising a base arrangement and enclosing two meshing auxiliary gear wheels. An end bearing plate is disposed on the side of the transmission housing which is remote from the pump housing. The two bearing plates and the transmission housing are designed to be mutually mounted with respect to one another in four relative rotational positions, each rotated by 90.degree. with respect to a primary axis of the gear pump. The pump housing and the intermediate bearing plate are designed to be mutually fastened to each other in two relative rotational positions, each rotated with respect to one another by 180.degree. about the primary axis.