OK. After some research would you agree that the picture of my grandfather gas station pump (est 1938) is an American hex or octagon 10 gal visible?

I think you are correct. It is the octagon(8 sided) version. I think it is a 2487 but could be wrong on the model number...

...if you can see four sides, it's an octagon...if it were a hexagon, you'd only be able to see three sides...

So it is an Octagon as we have established. I believe it to be an American 10 gal visible, couldn't find anything else that looked like it, handle, bonnet cover, skins, octagon and hose location in relation to the pump handle. Sure would like to get one some day but they appear to be pretty pricey.

Yey, found and picked up this 2487 at the Iowa 2020 show yesterday. Can't wait to get it back to TX.