its a p11 non lsd ,almost certain since those mounted from the top like that
strange it seems like its been altered to fit a b13...kinda halfassedly , it has a cable speedsensor but that can be switched out and the clutch fork lever seems like its been changed to fit cable trans...the fins on teh side of the case make me think its a p11 i forgot whether they had them or not or if it was some kinda jdm thing...for all i know it could be an sr16 but i doubt it since those came lsd iirc...as for teh diff. deffinately open. best thing to do is look on the bottom of the trans for two big ass bolts that hold some kinda check ball in