The fact is I saw this diff working and can confirm it was working before it was pulled. LSD's don't just randomly break/ stop working for no reason, wrong oil can be put in them to cause them to slip even though it hasnt been installed yet but it just doesn't make sense that's it's suddenly "bad". It literally takes 30 minutes to drop a s13 diff and replace it.I would test it for yourself I have seen mechanics lie about parts before just to get out of doing the work or sell a part, or they could be wrong themselves. Tons of possibilities

