Did the symptoms you describe start
post installation of the shaft?
I had a 1-pc that emitted a strange harmonic buss/drone that started in at around 100 MPH and progressively increased in DB level. I never took it much above 115 sustained as it was way to unnerving. I actually never thought it produced significant vibration felt through the car but the noise sure made it seem so. (I have a 2-pc now and that thing is silent and smooth at sustained high speeds and up to 140).
Anyone need a 1-pc? - perfectly fine for the street. The poor thing is just collecting dust in my garage since last spring
