Yes there is a plate. If it is a Open it will just have the gearing like 3.46 or 4.10. If it is a lsd it will have a s in front of the numbers. The problem is thatmany of these tags are no longer readable. So the best way to tell is just jack it up and with another person push the wheels in opposite directions, if it works then it is an open or it is a LSD with clutches that are no longer. If it the wheels will not spin in opposite directions then you have a working LSD. You could also enter the last 7 digits into realoem.com and get a build sheet and what was on the car.