simple. use a small screw driver and hammer to knock out the old one. Use a string or shoelace threaded down the hole and tied to the new one and pull it up through the hole. The bolt will hold it in place like it should once you tighten it. I had one of those studs fall out after I got my wheel assembly into place while replacing my struts a couple years ago. You might have to some how put pressure from underneath so you can screw the bolt on but I got mine to go. At least I think I got it to go. I should double check maybe I just got it almost tight and left it after a long tiresome strut job.