This document from Hardy Spicer was recently posted on Turbobricks.
It describes the common problems found with driveshafts and driveshaft vibrations.
This info may be useful for those doing gearbox conversions where the driveshaft needs modifying, e.g. T5 swaps.
https://www.waterousco.com/media/wysiwyg/pdfs/content/J3311-1-DSSP.pdf
