Getting a new fuel tank

I ordered an MTS polyethylene under seat tank and a 6-to-5 hole adapter for the sending unit. The tank hasn't arrived yet, but the pickup fitting is installed on it already so, I assume the tube goes to the bottom of the tank and has a screen on it. The sending unit I'm replacing had the pickup tube and the return tube built in. I don't need the return line, correct? I can just get a basic sender with the arm and the float, that's matched to the gauge, right? Is the return line just to route vapors back to the tank? Should I just plug it or would that be routed into a charcoal canister? Thanks.

 

So this is a '69 Willys? With an under-seat tank?

The return line keeps the fuel cooler. When you use it with the proper kind of filter at the engine, there is a continuous flow of gas from the tank to the engine and back. Has nothing to do with vapor. On an under-seat tank, all the fuel vapor goes out the vented gas cap into the air - there is no attempt at vapor recovery.

 

69 Kaiser I guess. I don't think Willys was a part of Jeep anymore by then, but I didn't know that when I joined the forum. Should probably change it...anyway, thanks for the info.