My very early1967 MF12H does not have the reservoir.
I simply remember being told I had a resevoir that I should fill, and I couldn't FIND it! Ended up adding ATF to the differential till it was full. Oh well, I ended up needing to change the diff oil anyway, and didn't run it that way very long. Just makes me jump in when I see questions about the MF 12 Hydro oil.