Thought I would post a quick how to on drive shaft replacement as my search brought up little details. It looks as though my drive shaft was removed by the dealer early in it life according to recipts & was not installed with the CV gaskets lined up or may have been relubed incorrectly or with the wrong lube. It seems that all the grease dried up causing both CV's to make the clicky clack esp upon decel, one even had rust inside (see pic). At this point I am not sure if the Audi dealer screwed the shaft joints up when they R&R'd the trans or if the CT coast line where this car lived destoyed them.
From research it seems that the center support bearing is the most common failure of the drive shaft but strange enough mine was good (no squealing noise or play in it)
I decided to buy a used drive shaft assy from a dismantler who seemed to specialize in drive shafts. This one was inspected & checked out well. The replacement unit was about 8 months newer than my original but the condition of it was mint compared to my 150k old unit. The used had no dried CV lube & 0 CV play.
This is much easier job with a lift but if not jack the car up on one side about 10-12 inches, place jack stands front & rear. I used an air gun but this could be done with manual tools although i'm not sure how you would get the exhaust clamp bolts out if original, I had to tourch mine off.
12 - 6MM hex bolts (6 on each CV side), 2- 13MM bolts hold center support bearing, Exhaust hanger bolts all 13MM about 8 total, need deep and extension for rear muffler hanger. Exhaust clamps 4- 17MM nuts i beleive. Mine were rusted to nothing. Head sheild bolts 4 - 10MM nuts.
This job is pretty srtaight forward with no real tricks. The one thing you may want to check before doing this job is the condition of your exhaust clamp bolts. If they are too rusted you may need to cut them off but there is not much room to get cutting equipment in there so a cutting torch maybe needed if you have the original nuts/bolt threads that have deteriorated.
Be sure to mark the line up of the shaft & housings with white out so you can put in the new shaft in the same fasion.
1: Remove exhaust clamp bolts where the system slides together.
2: Unbolt all exhaust hanger bolts, support the muffler with a jack so system does not twist & fall when you drop the last hanger.
3: Move exhaust out of the way to expose the heat shield. Remove the 4 heat shield bolts.
4: The drive shaft is now exposed. Put in neutral and spin the drive shaft down as you remove each 6MM hex bolt. Use a wobble extension to get the angle down so you dont strip out the Hex heads.
5: Remove the 2 center support bolts carefully as the drive shaft will fall from the rear first & possibly fall on your head. The front CV may stay stuck to the trans output so you may need to tap on it lightly with a flat head at the CV/trans tail point.
It should be clear to you on how to reinstall.
I attached some pics of my rusted CV side & the dried out lube side. The last is what the new & correctly lubed joint should look like.