Wow Jack, that was quite a history lesson. I guessing dating these pumps is an inexact science to say the least. You got me in the ballpark though (late 20's - early 30's).
I'm a big history buff so I appreciate your story of collecting scrap for the war effort as a kid. The great majority of us around today have no idea what that even felt like so it's great to have you share that bit of history and perspective with all of us.