that's a golden gate keg, the tapping equiment requires 2 units- the lower port is the beer out , the port on the top is the gas in. pressure and gravity taps are available, i own a set of each
the only brewing company i know of that still uses them is mcmenamin's based in oregon. anhauser busch used them for decades, most of the used ones i've seen have busch stampings.
hoff stevens kegs have a threaded fitting with 2 holes in it, the small hole is gas in, the large hole is beer out
both types of keg have the same shape, and are filled via the bunghole in the side which is sealed with a wood or plastic plug that is hammered in.