98 gt rear end noise

hello everyone, im new and I just bought a used 98 mustang gt. the cars is in pretty good shape but i have noticed that when im cruising and on the gas ill hear a whirring noise coming from the back end. I don't know if it the differential or a bearing or something of the sort. I know i need to get new rear rotors but i dont think that the issue because i only hear the noise under power.

If it helps ive also noticed that when i try to take off hard and get the back end loose its easy to get both wheels to lose traction when im going straight or to the left but when i take right turns reallly hard and clutch kick to get it to slide i can feel that only one wheel is spinning.

until i get this thing figured out im gonna be driving like a nun lol.

if anyone can it would be greatly appreciated.:smilie