I remember the Yamaha hydraulic drive AWD, I think KTM had a version too, didn’t Ohlins build that system? The Rokon moto tractor has a driveshaft through the frame with a slip clutch to a jackshaft to a chain driving the front wheel. Christini AWD also has a driveshaft and slip clutch with gears and chains to telescoping shafts that drive the front wheel. Looks like the SWM had a flex shaft that transferred power to the front wheel.