ok - the splash apron you talk of is rubber right? (It's not that blue metal curved piece above the running board seen in the middle right hand of this pic)
https://picasaweb.google.com/wmhatfield/RearFenderWork#5582221923616561362My truck is a dump, as such the fenders move up with the box, so perhaps the holes were factory made and were once bolted to the running board? In which case the apron would also not attach to the fender anymore. Do you agree?
Mark