Hi guy's, I have a AU3 Station wagon, that has an alloy tailshaft, with the big round thingy on the front yoke. It has big k's on the clock but still going great) I believe the big round damper thingy is made sort of like the old harmonic balancers, with a rubber insert in the middle? is there a possibility if this rubber insert was worn out or damaged that this could cause a vibration through the tailshaft/body? I have had the shaft proffessionally balanced at 2 different locations and they say it's ok, but do we know if the shafts are balanced with the big thingy on or off? As I still have this pulsating vibration/noise coming through the car between 60-110kms/hr,

could be the bush in the back of the gear box is rooted or the uni joint is f**k,

The big metal thing is the slip yoke damper and is on during balancing. Have you checked for play where the slip yoke enters the transmission. Its possible the transmission extension housing bush is worn.

I also had this problem when I first purchased my AU111 wagon approx. 5 or 6 years ago.
The problem is the aluminium tailshaft has an inner core that comes loose. No amount of balancing will rectify it, in fact, it disguises it because the shaft appears to be balanced, but in operation on the car the core is dislodged and causes the vibration or droning. I also had it balanced, but it made it worse. I had quite a fight with the car dealer I bought the car from, but eventually had the tailshaft replaced which rectified the problem. These shafts are quite expensive, I think around $1500!!
Hope this helps.
A problem I have at the moment is a rattle from under the car during most conditions. I have found I can reproduce a similar noise to the rattle by wiggling the tailshaft where it enters the gearbox, and suspect the sleeve is worn. But it does not leak. Can anyone confirm this? The rattle is very annoying.

the funny thing is,,,, the inner core in the alloy shaft is actually cardbord tubing...