I think the rails are on the outside of the stakes on pickups because it looks better and allows slightly more room for cargo.

I've seen stake bodies built both ways depending on the position of the stake holes. If the holes are outside the footprint of the bed, the rails are on the inside. If the stake holes are inside the footprint of the bed, the rails are on the outside.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)