pretty sure you've played with a well designed object and made it crap

sure 4x4's need to do this to compensate for lift kits, but it doesn't apply to our stock dattos, you think if Mr. Datsun Designer could reduce drive train loss by 1-2% by changing tailshaft angle he/she would not have known this and done this? i'm sure it would be at the optimum angle as per stock

no, i cant answer the question and google searching doesn't reveal anything, but you could check it by sticking your arm under any car that's just driven (rwd obviously)