I've worked on an early pushbutton (#1252) that also has an aluminum tank. It didn't even have a vent or vapor canister.
Check the routing of the hose and the location of the charcoal canister. The hose on mine goes up and over the gas tank shield, along the firewall to the canister on the passenger side.
If your gas tank has an extended filler neck installed, like mine, you will more likely have raw fuel overflow the vent every time you overfill the tank and you see fuel at the extended filler neck (which is above the roof of the tank).
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