I was thinking you might be able to use a nut the same as what's on it now,and cut a slot down one side to open it to the inside,then if it's treaded on you could use some Vice Grips to snug it closed tight to hold the end of the stud.It looks like there's not alot of stud above the nut now,but there may just be enough to grab and get the first turn.Just my thoughts,good luck. Barry