Update---The driveshaft balance seems to have done the trick. YAY!!!! I drove it down to work on our club project on Sunday. I got a little heavy on the go pedal and ran it up to 102(according to my GPS ap) and it was smooth.Not even the hint of a vibe. Balance was only about $60. New Ujoints and a new bushing in the tailshaft and also had to replace the Yoke because it was all knurled up. All totaled it was about $200. Money well spent. I'm may be ready for a track run.