As dimviii pointed, the basic torque split is determined by the gearing and this basic torque split is only applicable when the hydraulic (or another) lock is not applied. Once lock is applied, torque can flow in different proportion, being determined by the amount of diff lock and grip/resistence at each axle.
But to return to the original question, I can believe that Tanak used 30/70 mechanical split on this tarmac rally, providing more of a "classic" race car handling.