99 Tahoe Interior Droan?
 

I have a 99 Tahoe and when driving between 55 and 65mph I can hear an interior low frequency noise. the truck is stock with no mods on the exhaust. Someone told me that the roof rack causes this noise. During the time of this noise the truck has no vibrations at all. Anybody else have this issue. BTW my 91 Blazer made the same noise....