Since you don't tell us the application for the master cylinders in question any further help is guess work.
Dr Diff supplied the 15/16" aluminum MC. He doesn't state what the original application was for it but he lists that it works for both disc-drum and 4 wheel disc. It could be a Raybestos unit but there are no markings on it to determine that.
The reservoir is divided somewhat but when I fill one side, the other does fill up as well.
The 1 1/8" unit is a Raybestos model. It came in a Raybestos box. It is OEM for a Dodge D and W 150 from 1979-1993. It even is OEM for many vans of the same era.
