New to the site with a question

[Jcab256]

Hello everyone. I'm an on and off lurker for years, as I grew up with my dad owning a 68 C10 and always loved this style of truck. Well, it finally came time to own one of my own. I just purchased a 72 GMC C3500, camper special (longhorn) with a 402 automatic.

It runs decent, but needs a tuneup and lots of little repairs, so I'm likely going to have a lot of questions.

The first is, what rear end does this thing have? I've done research, and it looks like a 14 bolt FF, but I also read that those were only available from 73 and up. It's possible it was swapped in, but I think this truck is original.

Thanks!