Thanks. Two mechanics have now told me it's "internal." One said its a rod. Another mechanic said it might be the timing belt idler. I had a car with a bad bottom end, and as you said the noise was alarming to say the least. This just doesn't sound like that, yet. It's been getting worse over time -- I remember last summer thinking I might have a problem with oil pressure in the morning. Since then it's been getting worse, but very slowly and, again, compared to that car I had with a bad bottom end -- I junked it -- it doesn't sound bad at all.
The reason I keep asking questions is I remember having a Saab that I almost junked because it kept stalling and not starting. One of my mechanics kept replacing parts that never solved it, then I finally got it to a mechanic who really knew those older Saabs. He immediately replaced a cheap part in the fuel pump that solved the problem for good. Mechanics do make mistakes. I just don't like paying for them.
Thanks again for the extended post.