Those type of fittings are called "banjo" fittings and Chevrolet used them from 1936 ( the first year they offered hydraulic brakes) up into the 60's. "Banjo" fittings came in several various configurations. In the last few years, they have become harder to find. Some of the 55-56-57 car suppliers offer them, or at least ones that will work. They allowed you to install a line, or more than one line, and also gave you a spot to install a hydraulic stoplight pressure switch.
The idea behind these fittings is that one fitting could be used to address several different configurations depending on the vehicle they were used on. The key to using these fittings is to use new copper washer gaskets each time you install one of these fittings. Supposedly you can take a used washer gasket, heat it in an oven and successfully re-use it. I have never had any luck doing that and found that new ones are a better choice.
Raybestos and some of the other brake parts manufactures still list these copper washer gaskets in their catalogs.
Joe
