I have recently started to notice a small whining noise coming from the rear end, normally i would say it is an internal issue but it doesn't make the noise going straight down the road, Only does it when i turn a corner slowly like turning in a parking spot or the same when backing out.

 

Drain your rear differential fluid. Replace it with Mobil 1 75w90. Pray/Hope that solves it.

 

Do you have a limited-slip rear end. Sometimes, they can make noises and still be fine. Other times, they need some work. The best thing to do is pull the cover off and have a look.

 

...and while the cover is off, check the spider gears. The only time they move is when you aren't going straight.