Thank you for mentioning my shop
Nismo SSS is no longer available (unless someone has old stock). The GT is the newest Nismo LSD. Thier is several reasons to get the GT series over other setups, but mainly because it replaces Everything (not just the LSD).
Yes, it cost more... But its one of the only 2 LSDs in the world that survived a full season of Gymkana without being serviced. The other is the Cusco RS.
GT is non adjustable, GT Pro is adjustable 1.5 & 2 way by removing the passenger side Flange, *New GT Pro TT has a diffenernt plate angle, and alows for better corner speed & exit.
enjoy...