Thanks for that advice, I appreciate it.
I did ask my contact at the dealer (who is a Mustang guy who I like), after he told me that there is no technical bulletin on the issue, if I should bother to bring in the car to have the issue checked out, and his answer was, "you could, but they'll probably just tell you that it's normal behavior."
Is this really normal behavior for this car, or is something out-of-spec on mine?
Without seeing the issue myself that's tough to answer. I have heard enough stories about people being told something is normal that it sometimes seems if the car is not on fire you will be told it is normal. That said I still suggest having the dealer look it over first, for one thing you have the issue documented and they will look over the car and they may find something that can be addressed under warranty. If the noise you hear is in the driveshaft I suspect you'll be told it is normal. (Maybe it depends how you define normal. To me, often appearing is common. Supposed to be there is normal, not the same thing) The issue you're having is
pretty common, but not what I would call normal on these cars and if the suspension is all in good shape the cause is usually the factory 2 piece driveshaft.