Vario-Flex II with odd mount

[rybolt]

I recently got this lens as part of a large purchase. It is the 65mm Super Angulon version. My understanding is that it was available in different mounts. I have about 20 different mirrorless camera mounts and the only one that fit was the Nikon and it didn't lock into place as it should have done.
Does anyone have any experience with these and if the mounts are easily interchanged? I have 28 and 35mm Nikon PC lenses so I won't be keeping it but I would like to describe it accurately. Thanks!
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