I found a lightly rusted, not uncommon IHC wrench (at top, in picture below) with a loop handle being offered among the snowbanks at the local flea market a week ago.  After cleaning it up, it was compared with another single-shaft handled IHC wrench I obtained several years ago. Both wrench heads are stamped "5 E", and both wrenches are 11 5/8" in length.  The top wrench is embossed "7 1/2 E" on its handle, while the bottom wrench is embossed "7 E" on its handle.

I would like to know more about the equipment these wrenches were assigned to, and what period they were made in.  It's my belief that these wrenches are still fairly common, at least they were 10 years ago.

The one I saw on the WN site had a solid one and said it was the solid variation, I have a solid one to and didn't know of the other till now.

I've seen both styles before but never paid much attention to them. It looks like the loop handled version had to be assembled prior to opening the loop up on the handle. 

 Believe these wrenchs (BOTH LOOP AND SOLID HANDLE) were designated 8E( 12 in adjustable) by IHC. Irps lists many usages in his literature.
Earliest usage I found was 1901 for loop handle on Deering push header & binders.
usage listed for 19teens 1920S 1930s for both solid and loop handle.
There is also a 13071D (12 in adjustable loop handle) listed for 15-30 tractor and Farmall Regular 1924 Don't have 13071D wrench so can't speak on how they are marked.
8e's I have all have moveable jaw marked 5E. Non-moveable jaw or main body marked (7E) on solid handle and (7 1/2E) on loop handle.
They do measure about 11 5/8 overall.

I am not certain how one should designate these two wrenches, whether by the bosses on their handles or by what's stamped on the movable jaw.  The movable jaws on these two wrenches has "5E" stamped on them. 

I had pictures of the 5 E stamps on these two wrenches, but the Attachments option didn't work so I could not show them.