2007 Gmc 1500 V6 Vibration/drone

[pitbell]

Hopefully someone can help me on this site. I have a vibration/low drone sound that I can't seem to pinpoint where its comming from. I can feel it a bit through my gas petal and steering wheel. It only does it when in gear and only used to do it just before stopping and when you take off. Now it does it anytime you are around the 1200rpm range. It is driving me nuts and my dealership can't find it. Any ideas what it could be? It's a 2007 GMC 1500 reg cab short box 4x4 V6. I want to add that it is not a tire issue. It was doing it with the stock tires and it still does it with the new tires I just put on.

[stadt11]

Driveshaft, front-end alignment, wheel weight, warped-rotor, etc. That's all I can think of.

[Woodcutter]

Might be coming from the exhaust, maybe a heat shield or something if the vibration you're talking about is limited to certain rpm.