The Diff oil ir either needing changed or topped up, if its a whining noise that is.
the front diff is part of the gearbox and the diff/gearbox oil is the same-there is a dipstick on the offside of the box near the bellhousing.
0.8 litres
A noisy fuel pump in a 1995 Subaru Impreza could be a sign of oncoming failure. Check the pump for the source of the noise, and it is probably a good idea to replace it.
I also have diff noise in my VX SS, it sounds like bearings to me, maybe wrong. A diff specialist in Brisbane said about $800 if it is bearings, plus a complete service. I am looking for a good second hand diff, they are around $450.
Yes. It will bolt right in, but before you swap it make sure the final drive ratio is compatible with the rear differential. Usually it will be either 3.9 or 4.11. You can swap the rear diff too if you have it.
Look your diff seal...and check the oil in the diff...
Diff whine
it depends
Unless you can replicate the engine noise with throttle manipualtion by varying engine speed to 1200 to 1800 rpm, you have a driveline noise
tires
The pitch of the propeller causes this noise.
are you sure is a valve noise?? or is a piston slap?