Casting question

[385seriesHemi]

I have been reading threads on engine casting info and I read one that mentioned something about an "X" casted into the cylinder head of a 460 indicating a "factory replacement head" or "experimental version" was the other possiblity of it if I read remember correctly.My question is does this only happen with 460s or does this happen in each engine family when there needs to be a replacement on a particular engine?

[Mike G]

Perhaps it started at some point in time, I can say the FE does not have this though...
--Mike