I just got myself a 07 G35x 5at with 86k miles. Car runs great and was well maintained. But with all used cars there will be issues. When I come off the gas from any speed above 30 I feel a small tug and whine starts till a complete stop. If I apply gas during the whine it goes away. So it whines only when I come off the gas. Both front and rear diff have new fluid as well as the transfer case. Oil change and filter too. Thinking it could be a wheel hub the front hubs have been replaced. But the whine persists. I read through some threads an see issues with manual transmission or issues not consistent to mine. I really don't want to get raped at the dealer for something easily repaired. Any guidance would be greatly appreciated.

Try going past 30mph and shifting into NEUTRAL does it still whine?

I have tried dropping into neutral and the whine goes away. The tranny shifts perfect in reg, sport and manual with out skipping a beat. This is my first awd, and so diagnosing this issue has been difficult. I forgot to mention that after the tug and whine I can feel a subtle vibration or grind in the steering, brake and even the armrest when the whine starts and goes away.

I may be wrong but if you disengaged (going into neutral) the transmission, and the whining noise goes away. Your problem seems to be somewhere in your drivetrain (transmission, driveshaft, differential) here's another cheap and easy test. Remove your SERPENTINE BELT and go for a short drive (because your alternator will not be driven) and perform the same 30mph test. Let me know how it goes.