I have a glass bead blaster that will take that yellow and rust off in
two shakes of a lambs tail, but to answer the question it is called
a "box" wrench I do believe.
/ Identifying a wrench I found, yelllow CAT single box wrench?
yep a factory wrench. With something large like that often MFGs included a wrench. Farmall F-20's came with a few wrenches. Our IH hydro 70 came with two wrenches, both single box ends. They are still in the tool box on the tractor.
i think its cool the equipment MFGs used to do that on a regular basis. Pretty rare now days.
/ Identifying a wrench I found, yelllow CAT single box wrench?