ok i am pretty sure about lock-right in rear only. i have 4.56 gears and 31.6 inch tall tires,manual trans and a longbed std cab, it is NOT DD ,it is driven to and from trails as far as 80 miles one way and I do some tire deliveries once or twice a month the other 20 days a month it sits! is there a gear oil that would suit me better than stock for smoother locker operation?