I don't know what catalog you are using but the Classic Trucks online catalog show pictures and dimensions of the two different radiators. They mount differently.
1960-62 radiator 1963-66 radiator One is 23½" wide and has flanges where it bolts to the radiator support. The other is 25¼" wide and sits in a U shaped support. There is no way they will mount to the same support.
Like I said, year model does make a difference.
