BMW E46 320d rear end shutter/heavy vibration

[MacNel]

I have this nagging issue with my E46, the car has a really serious rear end shutter. It is barely noticeable when driving slowly with very little throttle, but if you accelerate really hard or tow a trailer, it becomes very bad. As soon as you are up to speed and driving a constant speed, it is not at all an issue, but pick up speed when trying to overtake, it comes back with a vengeance. Where can I look, it must be some mounting or something on the rear that causes this.

[MIKYZZ4]

I would focus on RTAB's, but an inspection of all rear suspension bushings would be my recommendation.

[MacNel]

You don't think it might be propshaft related? Maybe the centre bearing or the Giubo perhaps?

[MIKYZZ4]

I also would strongly suspect CSB or Guibo, if not for the absence of noise in the center console area, still perhaps possible.
A thorough inspection on a lift would be your best option to confirm.

[MacNel]

I did some testing yet again last night. The vibration occurs only from 50mph upwards. Below that is doesn't do anything. But, it gets worse above 50mph when you accelerate hard.

[Honolulu]

Testing be dammmed. Get under and look at all rotating components and see if you dshaft is dented, CSB failed, guibo gone. And check rims for bends, tires and sidewalls for signs of uneven wear or damage.