Hello I have a 2003 A6 and looking for the driver’s side axle. Where online can I get some reliable and reasonable parts?

 

GermanAutoParts.com is good for them. I've installed a dozen or so for people that have worked fine. You'll need triple-square bits for the axle-diff bolts. Use thread locker on the new bolts when you reinstall them - they have a tendency to back out if you don't.