it should say on the papers.
Sorry, I meant a used car where they didn't keep the sticker.
Call Mazda NA with the VIN number. They should be able to tell you what options the car was built with.
Here's what I remember about determining lim slip, verified by a quick google search:
Jack up both rear wheels. Spin one side by hand.
If the opposite wheel spins in the OPPOSITE direction, open rear end.
If the opposite wheels spinds in the SAME direction, lim slip.
Hope this helps.
This will not work with a helical (aka TorSen) LSD.