Originally Posted by crazzywolfie

it shouldn't matter which way the sending unit sits as long as you can hook everything up and the float arm has room to go up and down without hitting anythings. also sounds like you may have ordered the wrong sending unit if you need one with return line and it didn't have one. it should still do the job. i am cheap and just usually replace the pump/pickup screen. i don't replace the whole assembly unless the sending unit is acting up.