Hy Whimpy, that picture is of a balancer retaining bolt and I would not use that to try and turn a seized engine, I would jack the truck up and put some axle stands under it then remove the flywheel cover from underneath at the bellhousing and use a pry bar on the flywheel teeth to try and work the flywheel back and forth. Incidentally, that engine is not a 235, it is most likely a 230 or 250 it is not a 292. Your truck appears to be at least a 1965 model and 235s only went to 1962, 1963 in some 4X4 trucks, hope that helps.
