Which fuel line is which?

Got a 2000 Silverado, originally had a 4.8L. Doing custom fuel system, removed all the factory fuel lines . Using factory fuel sending unit (except for the pump), but didn't pay attention to which line was which when I took it all apart. The main feed line is obvious, being the largest, and I think the return is the other outer line, assuming the middle line is the evap line. Am I right or is the center line the return?


I'm talking about the ports coming right off the fuel sending unit on top of the tank.

I may be wrong but my guess is it’s vent. This is a fbody tank for reference. Attachment 86371

That looks just like the sending unit I have. Looks like my guess was correct, thank you, that's exactly what I needed!