as the title states, I'm not exactly sure when to use or why the a-trac that our "new" fj trail teams cruiser has. any advice or info would be appreciated. thanks!
In short, while in 4x4 Low Range, you can engage atrac and if/when you lift the front driver side tire or it looses traction, it will use the ABS to stop that wheel from spinning and transfer/focus the power/traction to the passenger side that has traction thus getting you out of the stuck situation. The same can be true with any wheel/tire that does not have traction.
You should be just fine... atrac (read brake system) only works when the system detects wheel spin. If there's no wheel spin then atrac does not engage. If you add a rear locker and engage it there will be no detectable wheels spin from driver side wheel to passenger side wheel and visa-versa. Lock the rear and atrac will still work just fine up front and your rig will be very capable!!!