Center Differential: 35/65 on most AWD cars. I like to have a little extra pull coming from the front wheels to give it that extra bit of acceleration coming out of the corners
Limited Slip: Same as for a road car, in fact I test mine on the road to get it right.
-Suspension-
Ride Height: Usually mine is raised up around 5-10 depending on the weight of the car and the amount of under/oversteer
Spring Rate: Soft. You want to compensate for the rough terrain and allow for a smoother ride, which makes for a more controllable ride
Dampers: Stiff allowing for greater suspension travel and again the smoother ride
Anti-Roll Bars: Soft letting the car transfer weight and sling the rear end
-Wheel Alignment-
Camber Angle: About the same as on a street car, 2 front, 1 rear to let the tires stay as level on the track as possible.
Toe Angle: I like to have about a .2 angle in the front to get more traction and pull coming around the turns.
There's my two cents. Hope it helps
-Brakes-
Balance: 6/4