ok for a while when im driving and i take my foot off the gas i get a whining noise coming from the rear i get back on the gas it went a way.

i changed the diff. fluid no change in sound. i did notice oil splattered up by where the drive shaft meets the rear end. i bought the car to a shop he took off the cover did not see any damage to the gears but he said something about the pinion was loose so he tightened it and he said the seal looked dry when the driveshaft meets the rear end. anyway when i left the shop the rear makes noise now when im accelerating and decelerating as where before it only made noise decelerating.

can i just buy new gears and will it fix the problem or is there more to it then just buying gears?

thanks guys.