Take a look at the Detroit True Trac which I have fitted front and rear. It is a LSD without clutches to wear as it uses pairs of "Helical" gear sets which bind together.
You dont have any handling problems that a full automatic locker has on the street or the extra wear on the tyres. I spoke to Detroit before buying mine which ones they would recomend from their range and they were it.
Here is more info on them
http://www.4wdworld.com.au/products/detroit/detroit.htm