I cut holes above the bad bolt/nut and replacedwith a nut welded to a metal strip. Belt the strip in a "L" shape, lowered into the rocker box and threaded the bolt. use anti-sieze. has worked for 18 yrs. and removed numerous times.It will work from the top or bottom just as well. The bottom is covered by the running board and the top by the floor mat. I just found it easier to work on the top than the bottom. The thing about using cage nuts instead of welding a nut to a hole is when you are installing the running board the cage nuts will allow a little movement to align better