All parts interchange. The Canadian model year was Jan to Dec, unlike the U.S. year of August to July, so the year changes are a little different.
Small towns in Canada had either a Ford dealer or a Mercury dealer. The Mercury dealers could not sell Fords, so they branded some Ford trucks with the Mercury name.
The 1961 Mercury Econolines were made in the US, and all were shipped to Canada. In 1962, Canadian Econolines (Fords and Mercurys) production moved to Oakville, Canada. This continued through 1965. Starting in 1966, all Econolines were made in the US. The Mercury Econolines were made from 1961 to 1965.
I welcome corrections and additional details. I hope to learn more about the Canadian Econolines.