Sorry that this is probably not much help, but I have seen this very valve, with the cheapo stamped lettering and ugly visible screws, in an old hotel somewhere, but I can't place it. I'm thinking it's a lot more than 20 years old -- if it's an older customer, often they don't realize that 20 years ago was mid-1990s. I'm guessing pre-1980 for sure, and probably a good deal earlier. Strom makes one that is very similar, without the volume control, cheapo lettering and visible screws, but with the porcelain handle with the little pointer on it, in similar design and similar shape of the face plate, which suggests that they were knocking off an old-timey design, as they often do, but whose I don't know... Does it seem like a high-quality valve with an ugly cover (like an old, long-discontinued Chicago Faucet or something, because CF uses that screw placement), or does it seem like a lesser-quality brand? (I'm guessing the latter from the deterioration of the trim...)
