My M 8540 (Kubota) has a limited slip front end. My dealer sells an after market GL5 80/90 brand @ $65 for 5 gal. It states an application for limited slip differentials. Auto Zone has 5 gal of GL5 for around $50. Am I to assume that all current GL5's are okay for the limited slip, or do certain brands add a component for the LS application to the GL5 stock? thanks bb