Help with APCO box end wrench ID

[Reefriot13]

So this was one of the first tools I found when looking for Plomb tools at a thrift store. I never gave it much thought until I stumbled on a picture of it on alloy artifacts. It's referred to as the first double Helix offset box end wrench. Made by Frank Mossberg/APCO. My question is my wrench is different looking than the one on alloy artifacts. I'm wondering if I have a an earlier version or a prototype made. I'm hoping somebody that collects these tools can give me some more information about it. here is a link to the photo on alloy artifacts.
http://alloy-artifacts.org/Photos/tools/apco_sb20_wrench_offset_pend_f_cropped_inset.jpg

 

[Reefriot13]

Besides the writing being in different locations on the handle the forging of my wrench is very crude looking almost like somebody took a socket and cut it in half and welded a handle on it.