Hello OF - I have created an overview of the Vacheron 4072, focused on steel (of which I can find very, very few pieces). This has details on the dial, hands, movement, case, etc., and includes all publicly known pieces I've been able to find along with sale prices. If you know of any others, drop me a note. I am also starting to aggregate information on known pieces that are both steel and gold (I won't be adding gold only). Enjoy everyone- Rare beauties indeed https://alphahands.com/vintage-watch-research/vacheron-constantin-4072/
Have added a couple more, including a "pre-reference" (1938) example I am trying to learn more about, as well as the kinda-related 92900.