Chasing a vibe

[RaysK20]

I have a pretty bad vibe happen at highway speeds above 55 mph. When your on the gas it does not seem to be there, let off and it shows up bad enough to rattle the transfer case shifter like crazy. I have new wheels and tires as of last week and the vibe did not change. I changed the ujoints and that maybe helped a hair but that was not it. The vibe is high speed not like a out of balance tire. I am starting to think a bearing is going out some place. I changed the oil in the 205 case and the 14 bolt rear recently, and niether smelled burnt. there might be a little up and down play in the case output shaft but it is little and the seal does not leak. Also the mounts seem ok, Any suggestions?