first of all you shouldn’t set torque share to 1.0 for both axles, their sum should be 1.0, in your case you get double power from the engine.
when it comes to differentials, locking torque is dependent on sth. called “feedbackTorque” which does not necessarily mean more load will give you more torque. if the wheel has less traction even with high load it might return lower feedbackTorque which results lower torque output.
I haven’t modified locked diff code for a long time so the difference between versions should be about the changes of “feedbackTorque” calculation. it’s quite a tricky concept and may not be physically accurate so you’re welcome to experiment on it’s calculation, see UFGearWheel::updateWheelFriction.