Retroluxe F100s and F250s were available in all forms 61-63. Flareside, styleside, and unibody and in all configurations except no unibody 4X4. Some 250 and I believe all 4X4s got the carry over box from the 59-60s I've only seen short bed examples of these though. All longbed stylesides from 61-66 I've seen have the 65, 66 style box on them. Your Particular truck may be a 63 wich has had the later grille installed. Alot can be changed in 43 years. If you have more questions post your VIN if its not on the glovebox door clean the right frame rail over the front axle. That's where you'll find it stamped. Oh Yah welcome to FTE.