Judging from the grille, it is a 1959 or 1960 model. The 1958 would have had a cross-hatch or 'egg crate' pattern grille, while the '59 and '60 Super Duty trucks had the horizontal bar motif the truck in the picture has. The '60 pickups, panels, and non-SD trucks had a revised grille, but the heavy F and T series trucks used a carryover '59 grille. Then again, the truck's finish indicates it may have been repainted a time or two, and it could be a '58 model fitted with a later grille. The hood emblems were similar for all three years.