Its not that big a job, I did both on the lightweight get a new bolt and nut to replace the one you finally have to knock out, fit the new panel with the bolt to the bulkhead loosley, then offer up the new piece to the chassis for final location, its then a case of prepping the chassis to take the new bit, hoping you dont find it too thin to weld without having to replate it as well
Have fun
btw before anyone says it, yes the lightweight is not the same size for the replacement part, I had to do a bit of trimming on the replacement part before welding it in, about half an inch off it, but better than trying to source a special panel for the l/w