Knocking while in 4x4

[ltd02]

I have gotten a bad brand new half shaft before on a Subaru so not impossible here too. I'd check the grease status like @KJowner said.

 

[KJBart]

I pulled back the boots and there was lots of grease in and around the bearings. I also pulled the boots on the old shaft that was replaced and it was full of grease as well. Still can't rule out the chance of a bad replacement shaft. Was curious though, what are the odds that it might be in the wheel hub itself, where the spline goes into. The reason I ask is the outer splines on the old shaft were rounded and wore down to half of what I replaced it with so thinking maybe the hub itself has more wear than normal and the spline slips in there to some degree. I can get a hub for ~$100 so I may give it a go.

 

[KJowner]

Looks like you may have found it.