I have an IH dump truck that had the same prob'. None of my tools would work.
I went to a big truck shop and they let me borrow two wrenchs that the mechanic had to modify (years ago) to work on IH starter bolts.
It still took some time for that one bolt because you can only turn it a tiny bit at a time. No other spanners (wrenches) I have, or could get would work- other than the mechanics' I'd borrowed.
Good luck with it! It will come out eventually!
Ya' just gotta love mechanical engineers. They all believe that all mechanics have a God given universal joint in their arms halfway between the wrist and the elbow. Also there are sockets that fit the thumb and forefinger.
Engineers should ALL have to serve an internship as a mechanic, just as doctors have to serve an internship.
Plus they should be subject to stoning or a bath of boiling Herring entrails when judged by a jury of their superiors..... mechanics.