Magnum swapping the 72 Scamp!
I have been chasing a vibration over 70 mph and happy to report I got it sorted. I went to a different driveline shop and had them look at my driveshaft / u joints.
It turned out the cheap u joints the other shop used were no good even tho they were new. So in went some spicer joints and a balance and voila, no more vibration. Good stuff.