I pored a bunch of the existing driveshaft threads and didn't see anything that seemed related...
I just had my van at the dealer to do the driveshaft recall. They installed a driveshaft with a u-joint and now we're getting a new vibration, most noticeable off-throttle and between 25-50MPH. It almost sounds like a helicopter is following.
Any ideas? My first thought is that maybe it's an imbalanced driveshaft, but that seems kinda improbable.