I got to test drive this morning after straightened axles, new wheel bearings, rebalanced tailshaft, new universals, new yoke and new transmission extension housing bushing.
While I feel there is an improvement it definitely still has a vibration. 80 and 115 kmph is the most noticeable. While it is no longer severe, it's still not right. I keep feeling like it's the tail shaft. I can see the vibration through the shaker when driving which continues when I put it in neutral and engine returns to idle.
Running the engine in neutral and moving through the rev ranges the engine is smooth.
I would like to try a different set of rear wheels for a test drive and see if that makes a difference. I may swap front to rear for a start. It's a good thing I drink! (not while driving).