If you have an LSD, there will be a little orange or yellow LSD oil sticker on the rear diff near the fill plug.
It really doesn't matter much, though. The Nissan LSD might as well not be there. An ARB locker is a bit of an expensive upgrade but if you plan to wheel much it's AWESOME.
Very nice looking 300ZX!
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Warning! Do not sear the top of your neck hole in the molten lactate extract of hoofed mammals.