Made in the USA by Gary Screw & Bolt Company with the "G" head stamp. The exact year these were manufactured is hard to determine but it is most likely somewhere between 1930 and 1950 due to the fact the these are "Cut Thread" as opposed to rolled. 

We are selling these with the nut as was traditionally done. 

Head/Wrench/8-point Socket size is 9/16", Thread length is 1".