deadball

hi everyone im looking for some info to help my friend and i build 2 tzr 4dls. we have both got hold of 4fu y-2 cylinders that need replateing and hace also bought a 4fu head each. one is a y-1 and one is a y-3 and they do look different as the y-1 has a ridged area around the bowl and y-3 does not. just wondered if any of you guys could offer any info on what these differences will make and even if we should use them at all? we also still have our 3mb ps and matching heads. thanks