I wanted to post an update that I had my new all brass replacement radiator installed yesterday. It was a unit I bought from an ebay seller, Tigris International. It came very well packed and the tech who installed it had nothing bad to say about it and it seemed to me to be a well made unit. I prefer all brass to the plastic/aluminum units which Behr and Valeo make for MB. There's a link to the listing in my post, above. You can also see that for under $300 delivered it was less expensive than either the Behr or Valeo replacements and at least this one can be repaired in the event that it leaks in the future. The seller offers a "lifetime guarantee" but I would be a little suspicious of this as the unit comes with no paperwork and does not even have a maker's name on it - but still...so far so good. It's not a really hard job to replace...about an hour's time on the 560SL, so I gambled that it was good and so far it has paid off!
I also had my timing chain, guides and tensioner replaced as well as motor mounts. My old 560 runs, smooth, quiet and like new again