Mazda Miata: Torsen LSD swap

Hello!
I'm about to put Torsen LSD in my open diff 2001 Miata.
I've found few of them, but only one complete, with casing and half-axles -
but much more expensive.
My question is: Do I need a whole differential; or just this part:
http://kempi.net/torsen.htm

Will it fit my 2001 open diff casing and gears?
Will I need any other parts?

Thanks upfront,
Kempi
'01 silver,IL