I had problems with the 7/16" bolts coming loose, wobbling, and then breaking off, I took the old bolts out, usually a drill will get most of it, then a dremel tool with a carbide bit for the rest (wear gloves!), and I drilled and tapped for 1/2" grade 8 bolts. I made some special keepers out of steel that fit over the hex of the bolt and put a small plate behind to even the load to the chassis, then lightly tacked the keepers in place onto the backing plate with a weld or two. The plate rests against the floorboard, so it will not spin out. Just weld enough to hold them down, easy to grind off to get the skid out as needed. Been a few years, still on the same bolts and keeper/plate set, had them off many times to rebuild stuff. Grease/Never Sieze the heck out of everything.