Abstract: A transmission particularly adapted for use in ultralight aircraft, air boats, home built aircraft or the like has a transmission case within which four gears are contained to provide the requisite speed reduction. A torque input gear is coaxially mounted with an output gear so that the transmission torque input shaft is in axial alignment with the transmission output shaft. A pair of intermediate speed reduction gears are laterally offset from the input and output gears and are mounted on a common jackshaft. One of the intermediate gears is belt driven by the input gear and the other intermediate gear belt drives the output gear to provide the requisite speed reduction. The gears and drive belts are toothed. The use of toothed drive belts and gears provide for positive drive of the transmission components.