Which fuel line is which on tank crossover.

[PAPA KENT]

I need some information for a quick reroute of fuel lines on my tank cross over switch. on my 76 gmc 4x4 my cross over switch is bad and of course only feeds from the left tank while the return line is feeding my right tank and of course i just noticed that i have fuel over flowing from my right tank.

there are 2 smaller lines going into the top of my cross over switch and 2 larger ones on the bottom, so with limited time tonight are the larger bottom lines the return or as i assume the smaller top lines to simply switch them for tonight so the fuel returns to the left tank.I had this same problem 15-20 years ago but i don't remember which is which.

Thanks guys.

kent.