66 GMC 5500? parts truck

[65 GMC]

I bought a 1966 GMC I'm guessing 5500 series truck tonight. It hasn't run in about 2 years and the brakes are down. I bought it for the grille and hood, also plan to use any other misc parts I can for my project. I'm going to try to pick it up this weekend if the weather permits. Looks to have a lot of good sheet metal on it' but I'm not at all familiar with this size truck. It has a v-6 in it, how do I tell which one it is? I will post pics when I get it home.