Hello Mlee,
You're right, these are unusual in that they have very limited markings and no model number. The style though is identical to a design they used for their models 69, 89 & 100. I've also seen same brush (without the model number) in NOS boxes that list the model number as 1460, 1466 and 1467. I'm not sure what the differences are, they look identical to me.
Thanks for the reply.
Funny thing is, I had never seen one of these brushes before I found this one a couple of weeks ago, and then this weekend I saw 2 more just like it at 2 different flea markets. It's too bad that there aren't more information on brushes.