2002 Subaru 104K miles manual transmission. It started with fixing the R front axle seal- then within 100 miles developed a hum in R Front- had bearing replaced- still have noise so dealer recommended replacing the transmission fluid. I know the vicsous coupler is bad because of thumping when making hard turns- I was advised that it doesn’t necesarily need to be fixed just that the thumping may be annoying. Could this hum/ rotational noise when going straight be caused by the viscous coupler?