Hirschmann 6000 U 485 Antenna for sale. It's in really good shape with no corrosion at all.
I disassembled, cleaned it out, and lubricated everything. I also tested it, and it works great. You will just need a mast, and it's ready to install.
I pulled it out of a 1978 280CE, but from what I understand it will fit most W123 cars (wagons excluded). Please double check fitment before buying.
Here's the Ebay listing if you want photos:
https://www.ebay.com/itm/Hirschmann-6000u-485-Automatic-Power-Antenna-Mercedes-Refurbished-Works-Great/174334672772
$130 OBO + shipping (lower price for forum folks). I want to get it out of my tiny shed, so make an offer.