Are fuel necks interchangeable in square door beds?

[Grit dog]

It was lucky I bought new hoses at the time, I managed to get the new pliable, smaller '76 hose, to stretch over the larger tank connection. I didn't know the size difference when I bought the tanks. The used tanks I got came with the filler necks with the plastic adapter to the body and a screw on cap. So what year are they?

‘84 and up.