Its pretty easy to tell if you have an open diff to compare it to, if you hammer it around a corner in a stock car the DSC light on dash will come on very early, and often, where as with an LSD its WAY more playful as it doesnt have the delta in rear wheel speeds, so doesnt think its as crossed up as it is
120 diff, 33107566169 , is 3.07:1
130 auto diff is 3.46:1 (manual is 3.64)
3.73 is what all the cool kids hunt for.
Pull it apart and have a looksee You'll need to figure what sort of fluid goes in it at some point.