Huret Duopar derailleur and Phil Wood disc brake (1977; introductions)
 

https://cimg7.ibsrv.net/gimg/bikefor...777acffb17.jpg

https://cimg8.ibsrv.net/gimg/bikefor...698b50a96d.jpg

I used a Huret Duopar rear on my '83 Trek 720 when I rode across the US in '97. It was relatively ancient by then but it gave good service throughout the trip. It does handle a lot of chain well. You do have to baby it a bit more than other derailleurs when shifting under a load. That's true for any rear derailleur but the Huret is a bit balkier than some under a load.

Huh, I've always thought that was a drum brake, but I had never laid hands on one to see how it worked. I guess it's sort it's own hybrid disc/drum beast and marketed as a disc.