Nope. I'm good. ops:
Your dealer SHOULD have a Hunter 9700 wheel balancer that measures tire road force. It's easy to spot, as it's got a computer monitor on it and a large roller behind the balance spindle. It could be a tire force issue, that no amount of dynamic balancing will fix.

If it's a driveline issue, it should be easily duplicated on a lift, as the differential is "fixed" in the car and won't alter pinion angle with the wheels dangling in the air. The "U-joints" are actually large rubber isolators, like an old chevy steering rag joint. I've heard they are nearly indestructible, but it could have been made wrong.

Does the vibration lessen/get worse with throttle input?