Jack up one wheel, and GENTLY accelerate the throttle with the transmission in gear. If the vehicle tries to pull ahead you've got a posi. Don't go much above idle, just enough to try to spin the jacked-up wheel. An "open" differential will allow the lifted wheel to spin freely.
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!