308 Evaporative Emission Control System

So today I removed my driver's seat to install the Birdman carpet munchers and found a disconnected wire on the bottom of the seat. I RTFMed and found the diagram for the "Evaporative Emission Control System". Holy cow batman. What a convoluted contraption to try and keep gas from evaporating after shutoff. So, it brings up a few questions

1) I assume this is carb-only. What year(s) did this system exist?
2) It explains the myriad of devices in my engine bay that aren't actually hooked up such as (D) in the picture.
3) So does this thing work on anyone's car still? Is it worth trying to get it working again or should I let it be?
4) What in the heck does that seat sensor do?
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That switch built into the seat isn't for the fuel evaporation control system, it's for the fuel pump (i.e., the fuel pump will only run with the key "on" and a person actually sitting in the Driver's seat). Most people/shops bypass the switch "closed" by hooking the wires together (because the whole thing is so flaky) although there is some risk with this (since the fuel pump won't shut off if the car goes upside down with the key "on") -- but it's no more risky than a non-US 308 that doesn't have such such a switch. If your fuel pump runs with the key "on" and no one in the seat that would confirm that it's already been bypassed.

You should worry about item D not being hooked up for the same reason -- you don't want fuel leaking out if the car goes upside-down.

All US 308 have a fuel evaporation control system, but it's slightly different for '73-'77 and '78-'79 model years. The diagram you show is correct for your '79 US 308.

'78-'79 US 308 have the seat switch, but non-US 308 don't -- not sure about '73-'77 US 308.

 

Item D has a bunch of hoses running to ports on top of the fuel tank. Are those ports open to the world or capped? Open is bad when the tanks are close to full because fuel would come out. It is also bad for the environment letting all the fuel vapors out. Could also be hard on the environment if fuel spilling out of the tanks sets your car on fire. If they are closed, how is the fuel system vented? No vents means pressure buildup in the tanks when they get warm, and they do get warm. How that escapes can be bad from flooding carbs to blowing fuel hoses.
I've never understood why people feel the need to disable the evaporative stuff. It is good for the air and your car and costs nothing in performance.