Mechanical fuel pump
Rockauto has pictures. You can see the difference in their outlet positions. The lines to carb dont interchange easily. I used the 73 up pump and lines to get the filter off the top of my 67 273 cast iron intake. Heat rises so when the engine stops, all the heat from water and oil would head for that filter. Helped to cure my fuel delivery problems back when I didn't know where the buy real gas.