Where do you live ?
It's what I'd call a "40" hub. Drum fits over the hub. (Hub is on the inside).
Brakes are 12x1.75"
Later had the hub on the outside but off the top of my head I'm not sure where the switch point is.
As a point of interest, the hubs/drums as an assembly are interchangeable for any year 1939 to 1948
Mart.
I had heard that, but was also told at one time the drum/hub needed to also match the backing plate as well?