Hy LewyBoys, those are standard Budd wheel inner and outer nuts, the hex nut holds the outer wheel on, the nut with the square head holds the inner wheel on. Sometimes the inner and outer nuts seize together, this can happen if the inner nuts were not tightened correctly. On the left hand side of the vehicle the nuts are left hand thread, on the right side of the vehicle the nuts are right hand thread, there should be an identifying "L" or "R" in the center of the square nut, hope that helps.
