Don't give me too much credit. I have barely enough smarts to go & look it up in one of my workshop manuals first.

I was surprised to realise that this 1971 car had smog gear that we didn't get untill the B210 model. Our B110's use a fuel system unchanged since the 1930's

The pipe that you need will have just one fitting on it & that is probably common to quite a number of US 'A' series models, so with a bit of luck you can score a pre loved one from a donor engine..

If your engine doesn't have this small fitting, but the firewall does have the flow guide valve, then I presume it's not the original engine.

Why would some US models have the valve, yet some 1200 engines not have the fitting? Different smog laws in different states? Was California enacting harsher legislation than other states in '71?