Drive shaft rumble
 

This happens when driving around 30-40 kph and foot off the throttle. Going down a gentle incline and foot off throttle at low speeds also does it. It sounds like the drive universal joints are a bit noisy at these speeds. Any accelerator or brake and the noise goes away. Took it to the Porsche agent, they looked over it when up on the hoist and found nothing wrong. Is this normal ? It's not a grinding or tinny nose but a quiet rumble. Maybe at low speeds, there is a resonance in the shaft and that is what I'm hearing.

Cheers Wallace

If your agent ruled out the axles it might be due to a wheel bearing issue. I don't know how it would be affected by the load and unload testing you've done. Others listers have addressed this problem...