PURPOSE: To further increase the road clearance of a propeller shaft and a transmission case by arranging the transmission case and a differential gear case in an inverted-L shape.

CONSTITUTION: A rear prime mover section is constituted by connecting an engine arranged laterally on a car body and a transmission case 14 fitted with a main gear speed changer 13 inside it in one body in a state that they are aligned in the left and the right directions of the car body in this order. A rear wheel differential gear case 7 is connected in one body below a transmission case rear extension portion 14a, thus the transmission cases 14, 14a and differential gear case 7 are arranged in an inverted-L shape in the lateral direction on the car body, thereby the road clearance of the transmission case itself is made high. A propeller shaft is made to be extracted from the upper side of the case by effectively utilizing the connection structure between the transmission case 14 and a clutch housing 12, thus the road clearance of the shaft is also made high.