A gear box assembly for a twin rotor combine is provided. The gear box assembly includes a two speed gear box having a casing, an input shaft, an output shaft, and a two speed gear assembly housed within the casing and operatively connected between the input shaft and the output shaft. The gear box assembly also includes a splitter gear box operatively connected to the output shaft. The splitter gear box includes a housing, and a splitter gear assembly housed within the housing and configured to split a torque provided by the output shaft between a first output shaft and a second output shaft extending from the housing in a direction opposite a direction the output shaft extends from the two speed gear box. The two speed gear box is pivotable relative to the splitter gear box housing.