1979 vs. 1980 jugs

[Incubus]

The Yamaha parts fiche lists a different part number for the 1979 cylinders and the 1980 cylinders. Can anyone tell me what the differences are? Would 1980 cylinders and pistons be compatible with a 1979 engine? Are 1979 pistons compatible with 1980 cylinders? Which pistons would be more compatible with a 1982 XJ head, the 1979 or 1980?

I'm still in the pondering and cleanup stage on my new project, but I only want to put the top end together once.

Thanks, y'all.

Patrick

[GNEPIG]

.. the part number might be different because the 80 cylinders are painted. i dont think there is any major differences between any of them except the late XJs have the intake ballance ports[YICS] but i think even those will interchange.