witch rx7 came with a factory lsd and is there any way to identify the lsd does it have any numbers on it or what

 

There's a sticky'd thread at the top of the 2nd gen tech section that will tell you what you need to know. Searching would be of great use.

 

Launch with the wheel turned completely in one direction. See if you leave two tire marks.

OR (the proper method)

Change the diff fluid, if it hasn't been done in a long time.
Jack the car up by the rear diff. Spin one wheel. If the opposite wheel turns in the same directiion, you have LSD. If it turns in the opposite direction, you don't have LSD. If it doesn't turn at all, you have a broken diff.