Have a 2002 A6 = Dealer says center drive shaft support bearing is worn out and it is all one piece so I have to buy the entire shaft. Just found a repair kilt on web that says I can replace just the bearing? Is this correct?

 

I know the bearing can be changed out on an A4 independent of replacing the driveshaft. They're full of it though - a one-piece shaft doesn't have a CSB - it's just a driveshaft from the center diff to the rear diff. A two-piece shaft has the bearing in the center between the shaft halves. That's the definition of a two-piece driveshaft, compared to a one-piece shaft.