USA, most passenger but not truck '32-39, I think none after that. Canada made them for all '32-48, but certainly made some of the '41-8 ones in iron as well. They made late types to fit 8BA type engines and made at least 2 kinds of 1CM ones, standatd and suto trans. Don't know if all Ford and Merc models '49-53 got versions of these or if some iron ones were used.
Canada made aluminum heads to fit all blocks as well but made iron ones too in most patterns, and only some of the late engines got them.