Abstract: A gear box trailer support having axially fixed gears in the gear box, including axially fixed larger and smaller input means on an input shaft, and axially fixed smaller and larger output gear elements of a gear cluster on the output cross shaft to the bevel gear drive for the elevating screw in the telescopic leg subassembly. The input gears are in constant engagement with their mating respective output gears. Shifting between high speed low torque output and low speed high torque output is achieved by axial movement of the input shaft within and relative to the hubs of the input gears. This input shaft has a male transverse drive pin which selectively engages cooperative transverse female sloped wall drive slots in the facing inner axial ends of the axially fixed input gears.