The original R90S mirrors, so from the era of the '74 model, were the "non nut" variety, with an elegant, slim curved stalk. However the "no nut" was a problem since that allowed the mirror to come loose over time and because there was no way to tighten up the mirror, it ended up flopping around. Then came the jam nut type as pictured, which solved the floppy mirror issue,?but with a larger diameter stalk. Again, functionally much better, but far less appealing.

I bought new mirrors from BMW for my resto project about 12 years ago and they were straight stalk (inelegant compared to the original elegant thin stalked originals), and came with a jam nut. So the replacements work very much better but do not look nearly as good as the originals.

I took the replacement mirrors and bent the straight stalks into a curve as the originals came which was a big improvement.

I saw where a?set of original new mirrors sold on eBay maybe 5 years ago, for some $500, or more, for the pair, undoubtedly because they were the original curved slim stalk type which look so good. ??