[eedgell]

I think the "posi" is short for positraction, which means positive traction to both wheels. If you lift one wheel off the ground, and the posi unit is in good shape, you should not be able to turn the wheel that is off the ground. The posi works on centrifugal force. At about twenty miles per hour the clutch system disengages, and then operates like a one legger does. The best way to tell is to pull the cover, but the test I listed above works well if the unit is working properly.