Found this on ebay, but was sold. Gives you an idea of what it looks like. View attachment 1716274790
Check with Classic Industries :1972 340 Carter Thermo-Quad Pump To Carburetor Line; OE Material
I've seen 2 piece lines that I'd imagine are for putting a filter in. The manual seems to show the filter before the pump but I've seen some pics on this site between the pump and carb which is where mine was currently.