2002 Audi TT Quattro Coupe - 225hp - 6SPD - 89k miles - ALMS Edition

I started hearing a weird noise coming from the rear end a couple days ago. It's kind of a whining/squeaking/rubbing noise (wa-wa-wa-wa) that is speed-dependent and can only be heard at low speeds (rolling to about 30 MPH). I can put the car in neutral while going down the road and it makes no difference. It happens regardless of turning, so I doubt it is wheel bearings. Also, it doesn't always happen and it seems to be worse when it is wet/raining.

I took some pics of my rear differential on both sides and you can definitely see oil/grease on the driver's side where the half-axle meets the diff (see attached pics). I figured it is either (1) a worn out differential seal leaking oil, or (2) a worn out CV boot leaking grease.

if it is the diff seal, which one of the following would I need to replace, the axle flange seal (Audi TT MKI Quattro 225HP Drivetrain Differential - 02D409399 - Axle Flange Seal - Priced Each - ES#271760) or the driveshaft flange seal (Audi TT MKI Quattro 225HP Drivetrain Differential ES#271798 - ECS Tuning

If it is the CV boot, would it be easiest/best to just replace the whole half-axle (Audi TT MKI Quattro 225HP Drivetrain Axles Left Rear ES#2561319 - ECS Tuning

Or, am I just way off and there's something else wrong?

I would greatly appreciate any input or suggestions! Thanks in advanced!

-Dalton

 

Well, I'm not getting any responses but I think I have concluded that it is just a screwed up CV boot. Since I am hearing noises I will play it safe and replace the entire half-axle. Thanks.