I think that is unique to the R75V8. The individual parts of the knob do not appear to be available separately, but I suppose you could have that part 3D printed? The chrome would be a problem of course. Complete knobs do come available now and then. I found one, but had to pay £55 for it 3 years ago IIRC. I have a spare therefore, but I don't intend to sell it. Sorry.
David