I'm running some 303 through it to clean up whatever metal was still in there, but this fall will replace that with universal trans-hydraulic fluid. It doesn't have to be Ford branded, any premium hydraulic fluid will be fine.
The Ford 1910 and 1920 tractors are actually from the 1980s model line, not the 1910s-1920s era.These two models have similar but not identical brake systems, with some interchangeable parts but different master cylinders and brake configurations.