FYI,
My experience has been that drive line noise's are "Gemlin's" that hide
in spots that you never think where the noise is coming from.

I had 3 sets of drive line noise in the past.

1) The rear axle outside (wheel) bearing was going, It sounded like the diff was going.

The next 2; I thought I had a tranny bearing giving up the ghost at 2 different times:
    1st) It was a u-joint on the short drive shaft between the Tranny & Trans Case
    2nd) I swapped in 4.9 gears in the Trans case and found that the rear output shaft bearing was "Getting Tired"
          After a complete rebuild (Including the new gears) "Problem All Gone"
Also in the past, I have had rigid mounted exhaust points cause some "At Speed" howls.

Good Luck,
CAPT

Thanks Capt for the info.  I'm starting with the RE and the TC and will follow the sound until hopefully I'll find it.  At 30 40 mph it roars and i can let off the gas or press in the clutch and it will stop.  Haven't had a chance to looked at it today because of Tornado warnings all day in my part of SC.