Whinng diff/overrun

Hi guys.My RR Classic makes a whinning noise from either the front diff or the third diff when coming off the throttle.I think my front diff is dry(no oil is leaking from it anyway) so Ive got me self some EP90.How easy is this to top up and will it get rid of the whine?If not does any one know what this whine is and how to fix it?its a 92 auto.Cheers!!!!

well me and me socket set and some EP90 are gonna have a crack at it tommorrow any way!

topping up or refilling either front or rear diff , or the transfer box for that matter is dead easy .
if your certain this is where the fault lies , i would be tempted to drop the oil from each unit in turn and first of all check to see if there are any silvery / metallic particals in them , if its got to the whinning stage i would expect to see something .
rick.

Couldnt get in the diff for love nor money(I offered both...) so ill get it done with me serrivce next week!Cheers anyway!