1985 300CD - 273215 miles.
I've tinkered with a few W123's in the past, and this one is the most rust-free I've seen. With the exception of some surface rust under the battery tray, (caught in time and soon to be remedied when the replacement arrives), I can't find any more.
I've owned the car for a little over a year now, and my family's current situation requires more space... so...
In that time, I've had the exterior repainted. I removed all the trim, etc. prior to having it painted, and replaced as much as I could with new parts (new emblems if available, new headlight doors, etc.). The motor mounts have been replaced. The alternator has been rebuilt. The throttle assembly from the gas pedal to the linkages has been rebuilt and adjusted. The heat/AC blower motor has been replaced. And the neutral safety switch has been replaced.
Everything else is either convenience or cosmetic - like the antenna doesn't work, and the doors/windows need new seals. And the AC compressor needs to be replaced. But nothing that prevents it from being driven safely.
I paid $4500 for it and have put over $2500 in it with the paint and repairs.
I'm located in Northport, Alabama. If you're interested, send me a message here. Thanks in advance