Found in the trunk of a 1969 or '70 280S or SE, forget which. No idea if it works. No idea if it even was meant to go in a W108. Backside has an antenna-connection cable, a yellow wire to a connector which looks like the power feed, and a double brown wire to a connector which I assume plugs into a single center-of-dash speaker.
If you're in the Seattle area and have a W108 (or other suitable car) with an empty hole where the radio should go, let's hook it up and see if it works. If it works, I'll let it go relatively cheap. If it doesn't, well, I guess I can sell the knobs...
A recent sale of a comparable radio (but, mine is in better condition, as it has the knob covers and pinstripe front glass, and there's no slippage when tuning it):
***edited: I now have a regulated DC voltage supply and a speaker; as soon as I collect some 14-gage wire and alligator clips, and an old scrap antenna, and I will test it.