On my way home from Moab I started getting some funny noises/ vibrations that I didn't get before Ldub lifted my VX in the parking lot of the Red Rock Inn. It was a super windy day during the drive and I got out and poked around to try and find the source of the noise. Mine ended up being the rear plastic inner fenders vibrating in the wind. The thing I'm talking about is actually the plastic, or fiberboard, "skirt" that is attached to the inner fender itself and hangs straight down. It was vibrating like crazy in the wind. Yours sounds a little more serious, but it might not hurt to take a look.