firstly how can i check my diff bearings? when the is car rolling around 40 mph u can really hear something grinding away quietens down a bit when u dip clutch or put un netural but deffo sounds like its coming from rear of the car checked wheel bearings etc they all seem fine no play or anything so i think its my rear diff any way of knowing its knackered?
also what diff will fit i have a 99 uk impreza

was offered a 95 wrx diff but didnt want risk buying it
all advise welcome

 

any1?

 

sounds like the problem I had.
I changed the rear diff and the propshaft and noise was still there.
I found it to be worn bearings in the transfer case.
Not too hard to repair,there are three bearings there to replace