My 2006 VE Commodore SS manual has recently developed a vibration, which is most notable between 90-100 km/hr in fifth gear. It is not violent and there are no other noises associated with it. I have tried rotating the wheels with no difference in vibration. I am worried it's something a lot more serious.
I would have the wheels and tyres balanced, then start looking at rear suspension bushes and drive shafts.
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