I think this series of optics was mainly a kit lenses for early 501 C and CM bodies, and never sold as a buy it alone optic
That's exactly so.
Though the later 501 CMs were sold with a CB lens.
Terence,
Bear in mind that what are now commonly known as "C" lenses were not called that until the "F" lenses appeared.
And then not on the lens itself, not officially, but in price lists and catalogues. First to distinguish them from the then new "F" lenses. Later because we al started doing so (and then in all kinds of literature, including user manuals and such).
Zeiss never used the "C" designation for these lenses at all.
So this "C" lens is really the first (and last) lens 'officially' designated a "C" lens.
I cannot remember (but that may well be just a matter of memory failing me) hearing or reading either Zeiss or Hasselblad calling it a "new C" lens.
This CF-stripped-of-F-functionality lens was meant - like the 501 C - as a cheaper entry level thingy.
That role was assumed by the CB line very soon after.