Update again. Even with Rubber mount, still could hear the shifter rattle at 2000 RPM of engine speed about 1100 drive shaft speed.
We had the drive shaft re tubed by the group that did the shaft originally. Better but not right, blurred rear view mirror at 65 mph. Took CVs off so all we had was shaft trans and differential. Still vibrated, this is when we did the rubber mount above. Took shaft out again and had it balanced, better but still not good. Took trans out and had the rear housing replaced (stripped drain plug) and some other stuff done. Mainly had the main shaft triple checked. Back together and still a small but annoying shifter rattle.
In a last ditch effort before ordering a CV drive shaft we had the shaft remade by another vendor. Voila, finally can drive the car at any speed with only a minuscule vibration and they just be the LS as I can hear the same harmonic in a lot of You tube videos. Took multiple attempts but putting the miles on now is much more pleasant.
Sad this forum isn't busier. Richard.