text:  You can pull, like, the lid of your toilet off, turn it upside down, and you'll see a date stamp right in there because that's very, very common. Even going back, frankly, almost 100 years, sometimes I've seen those date stamps in because it's the way manufacturers made these tanks. They always did that. Same thing with sinks, like kitchen sinks that are cast out of cast iron. I've seen the dates sort of actually cast right into those sinks. So that's one way to do it.