See my full answer of other forum Rich but for those on here.
All but late Terranos (and Nissan built Mavericks) came with Auto free wheeling hubs, the late models can with solid drive flanges.
Many people have "upgraded" to manuals because they are having trouble with autos. The rings can break but this happens through inproper use. Either engage 4wd gently on the move or if doing it when stationary you need to take up drive slowly initially to allow the hubs to lock in.
What tends to happen is people wander along in 2wd and then get stuck, so the stick it in 4wd and then give it a bit of stick to get it out. If they just took up drive gently before applying a bit of gas there would be no problem - better still anticipate and be in 4wd before you get stuck. The rings are only liable to break as they hubs are being engaged or dissengaed as once locked in they take no part in the drivetrain.