Why a suregrip?

7demon2 said
i don't know if they still do either. so why does everyone always ask if you have a "suregrip"? just why is the "suregrip" rear so good? it is a open rear from what i know of it. why wouldn't everyone want to just put a "posi" unit in it? i know with GM this is the first thing most everybody does......am i crazy or is this just me not understanding?
the new term at dodge is anti-spin diff.