Giant / Giant Grip Mfg. Co., Oshkosh, WI / (originally Giant Grip Horse Shoe Co.) / est. 1863 / merged with Challoner Co. May 1920 / Horse Shoes, Calks, Calk Tool / patent 682506 Sep 10 1901 Otto Swanstrom /
http://vintagemachinery.org/mfgindex/detail.aspx?id=1573 /
see also
Challoner / Geo. Challoner, Omro, WI / merged with Giant Grip Horse Shoe Co. May 1920 to become Giant Grip Mfg. Co. / see Giant Grip /
http://vintagemachinery.org/mfgindex/detail.aspx?id=1573 /
There does exist a connection between Giant Grip and Diamond Calk & Horseshoe Company:
Otto Swanstrom (patent
682506) was the brother-in-law of George Lindberg (patent
1320878).
I don't know Diamond well enough to speculate as to whether they were stamping those out for Giant Grip, but it certainly seems
plausible.
It appears that "Giant Grip" was offering a "No. 1 Farrier Tool" (calk removing tool) as well as a "staple puller" early on, so it's also plausible that they had in-house forging facilities capable of making a wrench.