its getting very loud...need a reasonably low mileage rear 3.9:1 for a uk spec '03 blob eye ,swapped all the original wrx rear drivetrain for an sti for brakes and suspension so the diff was swapped for the sti also.must have been high mileage cos 30k miles later and its almost unbearable. instead of buying a new one which i believe to be at least £600 can the rear diff be serviced ,or is there a place to getparts for a reconditioning.....noob so any input is much appreciated....