1980 Merc 115 hp, 6 cyl fuel pump

[bently]

I am planning on ordering a fuel pump rebuild kit and i would like to know what the difference is between the square and round pumps. If you look at the diaphrams that come in the two kits they seem similar. I would say by looking at my engine, I have the round version, it also looks like the pump in all of the part diagrams.

Thanks