5/16ths or 3/8ths fuel line

[Jakehaney]

I know it’s kind of a stupid question but did the 1966 1/2 ton pickup with the 250 I6 use 5/16th or 3/8th line? I stuck a 5/16ths wrench around the OD of my fuel lines and it was snug. Is it safe to say I have 5/16ths?

[Funky61]

Sounds logical to me Jakehaney

[Prowbar]

My 65 3/4 ton has 5/16" lines.