[A8] Driveshaft CV joint kit

[Ralf S]

I own a 98 A8 and my mechanic has told me that the CV joints at the
driveshaft ends (not the center u-joint) need to be replaced. He
couldn't find any after market kit for this and Audi only sells the
whole driveshaft. They have these kits for A4's and A6's, does anyone
know of a manufacturer or source where I might be able to find a kit for
an A8? 
 
All thoughts and help are appreciated.
 
Thanks
 
Ralf