VT Differential noisey - ready to go?

[wetwork65]

Hi - I have a 99 VT Calais S/C done 99000 km.
Seems to have whine from rear (differential I think) on overrun i.e down hills. Noise goes away when accelerating.
Changed diff oil but the noise is still there.
Anyone else found this? Do I need to worry about new diff?
Thanks for help

 

[NOGEN 3]

try jacking 'n spinning your back wheels by hand 'n c if there is a scraping noise, could b your pinion bearing- common on IRS centres...