Fuel hard line fittings

I'm adapting my old fuel system to a new 350TPI motor. I have stock hard lines for fuel that run up just under the passenger door on the frame and then connect to a half hard half braided extension. The braided part of these line are bad and need replace and they aslo don't use the fitting I need for my new fuel rails. My question is what size female fittings do I need so I can properly connect to the tube nut on the hard lines located on the frame rail? Inlet line is 3/8 and return line is 5/16 both have tube nuts and the tube is double flared. The dang fittings are expensive and I can't find anything around here so I have to order them.....dang it!