So I was on my way to a junkyard in downtown Austin when I noticed I kept hearing a faint clicking noise on my 91 300E.. I thought it was coming from the front of the car but I pinpointed it from left rear wheel.

I know it has something to do with the moving of the wheel because the clicks match the rotational speed of the wheel.. I took the wheel off and inspected and didn't see anything wrong. I looked at the axel boot and it looked dry and has lots of those super tiny cracks but I didn't see a huge crack or anything in it, but I'm starting to think the Axel may be going. Anyway to check to see what's going on? Can I take the boot off an inspect the axel or is that a no no? I've noticed the clicking has gotten louder since I first heard it. What should I check?

In the case that the axel needs to be replaced, how crazy of a DIY job is it?

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76 MG Midget
78 Datsun 280Z
86 Peugeot 505
01 Subaru Outback

“Owning a car is like owning a dog. Every now and then, it craps on the carpet — but it’s still your dog.” - Jeremy Clarkson