Im running ARB's in the front and back with 4.88 gears.... and that makes a HUGE COLLOSAL difference.  Night and day.  The biggest difference you can make to any 4x4.  I have engaged my rear locker and kept it in 2 wheel drive and gone further than my similar rig with open differentials in four wheel drive.  Ive done this same test with my jeep and it held true as well.