This is exactly the same problem we had in 60's /70's with Triumph Herald/ Vitesse, GT6 and Spitfire driveshafts.
The inner bearing [ball] never wore, but the bastid outer needle rollers used to disintegrate and take the shaft out, leading to great expense.
My personal remedy was to turn shaft to take a smaller inner dia and the hub to a slightly larger outer dia needle roller and make sure the Grease nipple was permanently in situ.
Modern thing of the time was all grease points had plugs and you had one nipple to be inserted in every point @12.000 miles and greased then replug and move to next one
One other point, I ALWAYS use this stuff for rebuilding
Everthing involving engines and metal to metal bearings>>
http://www.graphogen.co.uk/
Driveshafts and engines I built over 20 years ago are still running smoothly
thanks to that stuff
Fantastic work Pat
I'm following this thread with delight knowing there are still "
PROPER ENGINEERS" about