For a slightly twisted drive shaft causing bad vibrations at high speed (very noticable under a hundred at <cough>70) - would they be just as noticable at 60-70?

What might have caused this? There's been some other work on the car going on, it wasn't driven that much since the old clutch started getting pretty obvious (now got new clutch, and a new flywheel fitted as hairline crack reported). A suspension wishbone has been replaced as it was bent too after a knock, but otherwise nothing else.