differential calculus

[pu911]

Questions about 915 diffs,
In the old days if you wanted to know if a car had an open diff or a limited slip you jacked the back end of the car up and rotated a rear tire if the tires rotated in the same direction you had a limeted slip if they rotated in opposite directions you had an open diff, how do the torque sencing diffs (quaiffes etc) behave, I would expect that if you rotated a wheel nothing would happen to the other side. Insight is appreciated as always,
Happy New Year,
Phil