i hope this link works , here it shows this head being made after 1985 , or am i missing something
my heads have the 3 accessory holes shown in the lower part of the diagram (1985 on ) which is identical to the heads i have.
i dont have the mexican made stuff there is nothing marked to indicate that being the case .
my block is american made 350 4 bolt main , now a 355.
thank you for your input to my question.