Advice on LSD for new westy owner

[Plucky]

On the search for a limited slip diff for our 1993 SEIW

I do not know what fitment diff is in there at the moment? How do I tell?

From reading up I am thinking we are looking at 3.62/3.9/4.1

What would people reccomend? The engine we are fitting is a 240bhp Vauxhall unit and the primary use of the car will be on the road however we are keen to use it for trackdays etc.

So what sort of diff am I looking for?

Where is the best place to keep an eye out for one?

And if I am buying one from a forum or something how can I be sure it will fit our car?

We are also willing to compromise some driveability on the road to make a better drive on the track.

Currently the car has drums on the back which we are looking to change over for discs if that makes any difference?

Many Thanks