300SDL rattle from bottom-end
 

I was getting diesel last night, so I popped the hood, looked around and just revved the motor for the fun of it just to listen, and what I heard I did not like.

At the very front of the motor, at the bottom, below the IP, I heard a mechanical gargle/crunchy noise that increased with RPM. It sounds like a timing chain with alot of slack in it rattliling around, or...??

Any ideas? She's got 260K with the original chain.