Driveshaft issue? Speed related Vibration

Originally Posted by modme

My car just recently developed a weird vibration issue at high way speeds. At only speeds above 60+ mph, the car has a speed related vibration. The faster I go, the greater the vibration. This problem came on suddenly last week. Handling is not affected and the car does not shimmy. I dont believe its a wheel or tire issue, since none of those things were touched before the problem arose. Along with the vibration, there is also a low frequency hum that also gets louder with increased speed. The vibration has a really high frequency such that it vibrates the rearview mirror and makes the image blurry.

I know it's not engine related because the sound and vibration is not affected by RPM and remains constant with the car in neutral. I'm suspecting a driveshaft issue. Has anyone experienced something similar?