If it does it in park or neutral, it's very likely an imbalance of some sort. The 360 is externally balanced from the factory. I would look for maybe evidence the balancer has slipped. Maybe get a good picture of the balancer and post it.
If parked and I Rev to 2k I can feel it. But not at idle. I checked the balancer to see if it felt loose at all and seems good. I can’t get a good eye on whether it slipped or not. I’ll have to dig in more this weekend.
