my sending unit has crapped out and all the replacements have a return line,my only has 1 line.I'de like to upgrade to a 3/8's,who makes the best sending units?

Ma Mopar did.
PM Dixie, here on this board. He has some reasonably priced OEM senders.
ALL aftermarket senders seem to be Chinese made with mediocre quality.

I picked up a spectre premium unit from Autozone. It reads very accurately thru the full range in the tank and didn't require any adjustments. It was stock with no return line fitting. It didn't come with a new seal ring, or gasket so I reused my original. I think most say the metal is too thin on most new ones anyway. I also ran my own ground from the sender to the framerail with a thick wire and screwed to fresh and shiny metal. I think it's a much more solid.ground than that factory clip, which is important for proper reading

roe