I just bought a Supraphonic with a blue/olive badge and no serial # and am trying to get more info. It looks like it may be a 1970.

Yep. The early B/O badges sometimes had no serial number -mostly in 1970. They are more rare than drums with serial numbers, but there is no excessive value placed upon them as far as I know.

It became law that Ludwig had to include some kind of ID number on their drums. I can't remember the exact details of that -some kind of book keeping thing, I suppose.

So, the drums that made it out of the factory with no ID numbers were confined to early B/O drums. After that, by law, they had to be stamped with serial numbers.