21-speed: The Upton 180 used military-surplus gear boxes. The first gearbox offered four-forward and one-reverse speed. The second gearbox offered five-forward and one-reverse gear. This arrangement offered 21 forward and nine reverse gear combinations. The original rear gearbox was a Spicer from the LVT-4 landing craft. Later, Mack gearboxes from the M3 tank were used.