If those inner cowl panels include bends at the top end, they are from Dynacorn (see pic), and may fit more correctly than others, although I don't have experience with them. They just look more correct. Carl is likely talking about the ones that are about 3/4 of the full height (stop below the top of the vent opening) that come unpainted. They need work at the lower end, or splicing the short panels to them.
On your running board fastener issue, they're special bolts with an extra large head and a carriage bolt square just below that. If they're spinning in the hole, then you'll need to cut them off. Try tightening them instead of loosening to see if they will snap off. If that doesn't work, you can probably use a cutoff wheel on a grinder to grind the nut away, or carefully use a cutting torch to cut the nuts off. In any case, you'll likely need a new set of fasteners, and possibly repair the running board where the bolts go thru the support.
Kevin 1951 Chevy 3100 work truck Follow this saga in Project Journal Photos 1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car) Busting rust since the mid-60's If you're smart enough to take it apart, you darn well better be smart enough to put it back together.
