deceleration clatter

[ozburb]

On a trip from Qld to NSW, I started to notice a fairly loud clatter in my VE SS (170k km) when decelerating by manually down-shifting the auto. The noise seems to be coming from the front of the car (?) but the tempo seems to better match the car speed rather than the engine speed. Don't seem to get the noise if I leave the box in auto and use the brakes.
Anyone experienced something similar? Drive shaft related? or gearbox?
Thanks.

 

[ozburb]

turned out to be a bent heat shield at the back of the tailshaft near the diff. when under load, the two components didn't touch, so no noise. But on deceleration or when reversing, the reactionary force on the diff caused the tailshaft to move a bit causing interference with the heat shield. Just bent the shield more out of the way. Centre bearing showed a little wear but no concern.
The bent heat shield most likely caused by the bigger exhaust, and running over soemthing (the car has been lowered).
Hope this helps someone else who is starting to hear potentially expensive noises.