The word “transmission” is used for a device that is located involving the clutch and the propeller shaft. It might be a gearbox, a torque converter, overdrive, fluid drive, or hydraulic travel. Such a gearbox attributes driver and pushed shafts that share the center line (coaxial) but function independently. https://gearbox75307.mdkblog.com/39626626/gearbox-an-overview