Ditto on the additive- - - -it's needed to prevent the limited slip clutches from chattering in a turn- - - -the sharper the turn, the more likely the clutches are to shudder due to the speed difference between the axle shafts. This is true regardless of whether the limited slip system used discs or cone clutches. Yes it is possible to turn the wheels independently of each other, but it takes more torque than you can put on the wheel by hand. Some manufacturers used to publish a torque spec to check the clutch pack preload- - - -I seem to remember it being somewhere in the range of 100 ft-lbs. A torque wrench adapter was bolted to the wheel studs, and one axle was forced to turn with the other wheel on the ground.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!