There are a few ways to tell if your Datsun 280Z has an LSD. One way is to check the vehicle's identification number (VIN). If the VIN ends in "A," then the vehicle has an LSD. Another way to check is to look under the car and look at the differential. If the differential has a small metal tag attached to it with the letters "LSD," then it is a limited-slip differential.
If you are unsure whether or not your Datsun 280Z has an LSD, you can contact your local Nissan dealer and provide them with your VIN. They will be able to tell you if your car has an LSD.