I don't know if this helps or applies. On the '41-'46 Chevy C.O.E., The radiator has a smooth neck. A short length of straight hose connects it to the filler neck (with cap).
A bracket or clamp secures the metal neck and cap to the firewall.
I'm not looking at this setup at the moment so I am going from memory. I never understood why the extra upward extension was needed.
Many miles of happy motoring