Now that I think of it, a open diff will send power to the place with the least traction. Usually the front since weight transfers to the rear under acceleration.
A thicker diff (like a posi or mech locker) will apply power equally... more to the rear under acceleration and that would allow more front traction and steering.

Maybe Marcus will get our heads straight on this

I think that goes back to try zero and ten pins to see what it's doing to the truck.