Need Some Expert Analysis for You Truck Gurus

[CountofMonteCarlo84]

A while back I stumbled upon a truck at a show the owner indicated was a 55. It wasn't exactly for sale, but I got the contact information and after several months he has agreed to sell it. I was actually looking for a 67-72 C10, but fell in love with this truck. The owner indicates it is a 55, but I know it has a 57 grille. When I mentioned it the first time I saw the truck he thought his grille was for a 55 and did not really say much else. I just want to determine whether it is indeed a 55 or actually a 57 (I don't care if it is a 55 with a 57 grille, but I assume there may be title concerns if the title says 55 and it is actually a 57 altogether). I do not know these trucks well enough to spot any differences. Therefore, I am asking the gurus here to please help me determine whether this is indeed a 55 or a 57. If the pictures I have do not help, let me know what I can look for to determine it or if there is something with the serial number I can check (also where should the serial number be). Thanks for all of your help.