Searched the forums but did not see any about this, but may have missed it. 05 TB LT w/ 200k miles. Once warmed up and around 1200 RPMs or higher, I hear a hum from the drive train. But only under load. If i take my foot off the gas and the RPMs start to drop even a little bit, the hum goes away. i could coast down an incline and no hum. As soon as I give it gas, the hum is back. Consistent hum. And it is noticeable even with the windows open or closed and radio on. But it is not extremely loud. But my wife did notice as well. Pretty much it sounds like it is coming from the back end, but I know how sound can travel. Have always kept up on maintenece and fluid changes and truck runs fine. I just have a feeling something is going to go. Anyone else experience this.