A gear transmission for the final drive of a heavy automotive vehicle, such as a tracked vehicle, comprises two planar gear sets each having at least one gear rotatably supported on a respective housing part. The two housing parts are rotatable relatively about the axis of a coupling shaft to vary the interaxial spacing of input and output shafts connected to the respective sets and offset from the coupling shaft. This allows the interaxial spacing to be adjusted for various vehicle requirements without varying the transmission ratio.