Most of the early machines sold by Wards were made by National. Sears used quite a few different manufacturers. And often at the same time. They used Davis a lot early on and then switched over the White/Domestic. I've seen Sears catologs that show machines by several manufactures, and showing 4-5 different shuttle types for their machines.
Once we get to post ww2 - they are almost all Japanese made, and then who knows. . .