Carter rebuild

That carb is much older than the truck. Where you see "6316s" that's what you need to get the right kit.
That carb is at least 10 years older than the truck, not saying that's a bad thing at all. By then most 318s were using the Holley 2280 rather than the Carter.
I can tell roughly how old by some of the external features of the carb. By 1976 most BBD carbs were more "squared off" looking and had an inspection cover where the accelerator pump adjustment and metering rod stroke was adjusted,
that cover was held in place by a single screw.