Very simple.
Put the car in neurtal, jack up either side (one tire) If the LSD is set up correctly (free) you will be able to turn the tire with some feel of resistance caused by the spider gears turning and the viscous interface on the clutch disk and floater plates.
If you try quick increases in the rotation it should lock up, in either direction.
JJ:
You know YOU really didn`t know did you, and you were supposed to be the great expert!
"Mean Old Bastard"