acceleration whine
 

Can anybody shed any light on a rattly whine, under acceleration only, on my s40 2.0 diesel?
It has 98k on the clock, a 2006 model.
The problem is not heat shields as i first thought, it seems more like a driveline issue, maybe a main shaft bearing, or drive shaft?
It can only be heard when when accelerating.
There are no other signs when idling, coasting etc.
Any feedback much appreciated. Tah. Clint.:D