Another newbie question....what is this?

[Buzzman]

So, um, I don't know what this is. Next to the radiator on the driver's side is this cylinder with a few vacuum lines going to the carb. It's a 79 Chyenne with a GM Crate 350. My first thought was A/C, but I see no mention of it elsewhere. Trying to get rid of some stuff under the hood that I don't need...maybe this is one of them? Forgive the dumb question. Thanks.



And here's the truck, just 'cause I like to look at it.