I am looking for info about a #462264 head. The ones I have say "Hencho in Mexico" on them and have a date ending in a 4, as in 1994 most likely unless someone can confirm when these heads began production there? Anyway I know about how these are among the worst heads available but for my general use I think they will suffice but my question is does anyone know if the casting changed from the thin, crappy type in the originals to better, heavier castings in Mexico? The last I knew the heads Chevy was making in Mexico were the 993 castings which many people like. Does anyone know when or why Chevy made this change? These heads are on a Goodwrench or service block which likely was also cast there. Any info anyone may have on this is appreciated. Thanks.