Since the control arm is threaded on both sides, and the lower knuckle is also threaded, I do not see that the torque is critical. Just get the nut tight, insert the cotter pin and it will never accidentally loosen unless you remove the pin and loosen it. The nut on the bottom of the king pin is a critical torque since it tightens the steering knuckle onto the tapered, bottom end of the king pin.