Help with weird vibration

My poor truck is not in good shape. Yesterday I drove to Tallahasse for the FSU game and on the way I started noticeing a werid vibration on the seats, gas pedal/brake in that area. It seems to do this while letting off the gas either letting the engine slow itself down or braking. Usually vibrates then turns into a grind/scrub noise like you'd hear when your tires rub plastic fendor. It only does it when decelerating. Im just worried it might be a tranny or a drive train type problem, but does anyone have any experince with this?

 

Wheel bearings maybe? Had to have mine replaced they were creating a slight vibration grinding noise...

 

Pretty sure its not, Its more towards the center of the truck like drive shaft/ front end area

 

Hmmm there is a well known driveline vibration... Search it youll see!