Any information on the 4-wheel drive system? Is it an electronic limited slip differential or does it have actual differential locks (rear and maybe front)?
Since it's a skid-steer (steering consists of slowing the rotation of wheels on side you want to turn towards) the whole setup is probably different. I'm guessing it has two hydraulic motors, one for the left side and one for the right side, powered by a hydraulic pump driven by the engine.
It has skid steering, so left and right sides are probably locked.