Maker of this crow's foot wrench?

[junkman]

I have this old crow's foot wrench marked A 504. I've seen an identical wrench with the same numbering that was identified as belonging to a Gehl implement, but what has me flummoxed about this one is the maker's mark -- a C encircling what appears to be a combined B and D. Does somebody know this toolmaker? I've drawn the mark to help.