Locking the rear end

I have run a few of the original clutch type sure-grip like was suggested from Dr Diff. I ran one in the rear of my Willys wagon on the street and off-road for years.... GREAT UNITs! I have one in my Barracuda now and would recommend this style over a lock-rite on the street. As was already stated, any type of "locking" differential can be fun when wet! The tighter they are, the more they like to slide you around. Set up properly, the clutch type has great traction on the dry street and very drivable in the wet.