This photo is taken from Mercedes Source where they will sell you a kit with instructions. A good information source, but you must pay for it. Here the unit is about $90. Personally, I would trim the wires and also save the connectors.
So one of the problems on my 380SL that came from California in February was that the rear automatic antenna flopped up and down. That was a problem because it resulted in very poor AM reception, and I am a big fan of listening to the Reds on WLW and Colin Cowheard on ESPN radio.
OK so I needed a replacement unit. From what I read, don't even think about rebuilding the original Hirschmann unit unless you have more money than sense. The best strategy is get one of the Hirschmann replacement units, made in China. If you buy a unit from Mercedes Source with instructions, you pay $90. I bought my unit new on Ebay for $45 including shipping. That is about right, as I installed one of these years ago on my 1971 Porsche 911. Taking the old unit off is easy -- look inside -- mine was all cruded up. I'll play with it sometime in the near future, but no hope of bringing it back to life.
The new unit isn't as easy to install as you might think. For one, the Hirschmann instructions are totally visual with diagrams. So it took me a longtime to understand what parts to use to fasten the antenna to the body of the car. The 0-35 degree set up has a rather cheap stainless top, so I opted for the all plastic set up. Play with the spacers, there are three and you can mix and match to suit your needs.
The other issue is wiring, made complex because Mercedes has a dash switch that on the original model enabled the owner to bring up the antenna to half full extension. What that means is that you have 5 wires on the original, but only three on the replacement antenna. I opted to take the wiring coming out of the original Hirschmann unit so I could keep the connector plug functional. I connected black to brown (ground), Blue to yellow/green, and white to red, with the black wires just taped.
There are plenty of queries on the web but little definitive instructions.Whatever you do, take your time, work at a slow pace, always think of doing work on a level of quality that respects the Mercedes tradition.