E39 whirring noise

[Gad-Westy]

Just been out in my dad's 528 auto. It's got a fairly loud whirring noise coming from, I think, the gearbox. Gets louder with speed so likely something prop or diff related. Any common problems that it could be?

[Pickled Piper]

There's also a centre bearing on the propshaft. I don't think it is expensive or difficult to change.

pp

[Gad-Westy]

Cheers, will mention it to him. Seems to be getting worse.