Another agricultural wrench mystery (or not)

[Wrenchmensch]

I found this familiarly shaped wrench at a flea market last week in York Co. PA. The "M23" boss on this wrench is unfamiliar, and I could not find it in either of Pete Rathbone's volumes.
There is also a faint stamp, B inscribed inside an O, to the left side of the boss. 

Does any body know who made this wrench?

[lzenglish]

It sure does look like a Planet JR. wrench, but you probably already know that. I'm not familiar with the numbers you gave on it.

Wayne

[rusty]

There is a comment in a post on Yesterdays Tractors that seems to imply that number is appropriate, not proof, but a hint perhaps...

http://www.ytmag.com/memo/messages/814.html

Letters in circles seem to be foundry marks more often than not, tho I dunno who's (B) is..

[bird]

HMMM, I think I have a book that talks about that wrench, but, it's "locked" in the hardware store at the moment. I'll try to look it up tomorrow.
cheers,
bird

[Bus]

It's on my "orphan" list.

[Wrenchmensch]

Mine too, Bus