With the vehicle on a lift in 'Park' or gear, (so the Driveshaft can not rotate) an open differential will cause the tires to rotate opposite directions, if it has a mechanical LSD, and it is in Park or gear, you will not be able to rotate either tire by hand without considerable effort(to overcome the clutches or springpacks, depending what manufacture of LSD it is)...with the same LSD equipped vehicle in Neutral, both wheels will then rotate in the same direction if turned by hand...