Well, cheers for the help. I think I have decided what diff I want .

I had a chat to CTS about rebuilding the 'box and fitting an LSD (if I sourced one to be regelled or if he supplied one) and he suggest that my car wheelspinning could be down to the springs being too hard up front. I doubt this is the case (it does hop up or down, it just 'smoothly' spins a wheel on the move), but I shall investigate this before getting the diff done.