1972 C3500 402 4spd with 5/16" fuel lines?

[jumpsoffrock]

'72 California truck, SPID says it all.

My fuel gauge sender is bad, and everywhere on the internet says I should have three lines, Rockauto only has 3-lind fuel pumps for my truck, and every sender for my "V8" truck is said to be 3/8". The internet even tells my my sender should not have a flare nut on it, and that it simply connects with a piece of hose. Nope not my truck......what the heck is going on???


What have I found on this truck? The sender is 5/16", if I hold a 5/16" open ended wrench over the line it fits around it perfectly. The line bolts to the truck frame line, no rubber hose connection.

My fuel pump only has 2 lines, there don't appear to be any stray lines that look like they were hooked up and then abandoned at any time.



I really don't want to order the wrong part, but my truck is some kind of anomaly, can someone confirm if they have 5/16" factory lines in a big block truck? Thank you.