The stock sending unit has a 3/8" outlet. If you go with the Hemi 3/8" fuel line to the fuel pump and then 5/16" from the fuel pump up to the vapor separator, nobody will notice or it wouldn't matter if they did. In fact, I thought I heard the 70 sixpack's were upgraded to the 3/8" fuel line and have a 3/8" inlet in the fuel pump? On the other hand, the 5/16" always worked fine for me on my A12.