Fellow T'er is asking me about these, and I am not very knowledgeable, ergo, I am throwing down the gaunlet to those better able to discuss intelligently....how long made, differences, etc etc
I believe that heads that were actually physically made in Canada started in 1913....before that, the "Made in USA" was ground off the heads when they were installed in Canadian cars...
I am not aware of any actual differences in the heads, other than the name.
would the UK have "Made in England"? etc...
Here is some pretty good info for you:
http://www.modelt.ca/background.html
Just click on the Ford of Canada on the left side column......