[gofastralph]

Okay so here's the issue. My 4r70w transmission has about 60,000 miles on it. When driving it shifts fine up until overdrive. At that point the engine revs so about 2300 rpm before going into overdrive, then once overdrive does ingauge I feel a vibration and hear a clattering noise from under the car. This continues until I reach about 50 then everything smoots out. Then when I excelerate it will down shift and I hear the noise again and feel the vibration. What could it be? I've heard that the u-joint can pose these types of vibrations but why only in overdrive and what is the noise? Any help would be great.