Here is a comparative experience, at least:
I just had the timing chain replaced on my '92 500E, by a dealer, at 103K miles. The engine and trans stayed in the car. The heads stayed on. The cams were removed and replaced. I don't think the radiator was pulled. The front cover was pulled, but I was not made aware of any gasket mods. The mechanic gave me a copy of a diagram page in the service manual - B. Engine 199.97/98, Page 2, "copyright DaimlerChrysler AG 18.06.2001 CD-Ausgabe G/05/01..."
It shows the layout of the chain and rails. He replaced the six upper rails (the smaller ones), and the tensioner, but NOT the lower rails (parts 3 and 29 on the diagram).
Total cost was $1,511.33 labor and 452.98 parts.
That was about 1,600 miles ago, and I just heard the dreaded clatter again yesterday.
1995 E320 Wagon Moonstone Grey/Parchment 106K mi.
2007 E63 AMG Graphite/designo 75K mi