M235i LSD question

[Joratk]

How do you tell which M235i's have the optional M Performance LSD in them? I find dealers don't list them separately in their ad so I never know if it has one or not.
Do all cars with the M Performance pack have an LSD?
Can cars without the M Performance pack still have an LSD?
Would the Quaife LSD be better than the M Performance one? So maybe I should purchase a car without the LSD and just fit a Quaife one?

Any answers are much appreciated!