The '76-'77 carb set and the '78-'79 carb set are as different as night and day. '78 was a "big change" year for the BS38s. They got that new style slide that retains the needle with a snap ring and all different jetting. Overflow tube in the float bowl was eliminated along with it's outlet nipple on the bowl bottom. External vents for the float bowl area were moved to inside around the bell mouth.