I had the clutch release bearing renewed - the old one was loose and dry, and this has eliminated the spinning-down noise, and greatly reduced the rumble when the engine is running in neutral. But the vibration is still there. However, I happened to notice that it got worse after I loosened the fan belt, so I'm now suspecting the alternator or water pump bearing, or the viscous coupling on the fan. Will check this out when I get time. I have a spare water pump, alternator and viscous coupling so if my suspicions are correct, should be sorted soon.

Daniel

Yep, the thrust bearing was favourite.
All you have to do now is wip the belts off one by one and run the engine after each belt so that it isolates each component.
Your getting there.
Cheers
Ian:thumbup1: