Man I feel your pain chasing down vibrations...been there done that. I'm sure you have but just in case, make sure there isn't any play in your rear axle bearings. I've found pushing straight up and down on the raised off the ground tire with your hand is the best way to feel if there is any play at all. A very small movement of the bearing will vibrate..believe me...
Sweet about the 9.5s on the front, been there done that too!!
