If in the angle strip was reversed front to back (and as such left to right), the single thru hole in the angle strip would receive the rear fender brace. In your case maybe the angle strips were used in reverse.
~ HB 1966 Chevrolet K-10 | Ghost: formerly Flappy Fenders | In the Stovebolt Gallery 1962 Chevrolet C10 1962 Suburban