Replacing the fuel and brake lines?

I don't think you have quite understood what I'm asking for. Like I said, on the underside of the driver side, there are five tube lines as the picture I sent in the previous thread illustrates. After doing some research, I have been able to identify what 4/5 of those tube lines are, including their respective Toyota part numbers. What I'm looking to determine is what the fifth tube line represents.

Here are the details of those tube lines in random order:

1) Fuel Main Tube Part #: 77251-07010

2) Fuel Return Tube Part #: 77255-07010

3) Rear Driver Side Brake Tube Part #: 4732207010

4) Rear Passenger Side Brake Tube Part #: 4732107010

5)?

Can you please identify what the fifth tube line is including its respective Toyota part # and what it's called? Additionally, if you could provide a diagram that illustrates those tube lines in the underside of the car, it would be greatly appreciated. Unfortunately, the diagram you provided does not meet my purpose.

Thank you

Please take a good look at the attached picture. As you can see, there are a total of 5 tube lines on the underside of the driver side. I have been able to determine that 2 of them are brake lines and that 2 of them are fuel lines (the main fuel line and the return fuel line). So, now we are left with only one tube line that remains to be determined what it is. The question is what's the name of it? Once I know what it's called, then I can look into finding out its respective part number, so that I can buy it.

Thank You!

Please take a good look at the attached picture. As you can see, there are a total of 5 tube lines on the underside of the driver side. I have been able to determine that 2 of them are brake lines and that 2 of them are fuel lines (the main fuel line & the return fuel line). So, now we are left with only one tube line that remains to be determined what it is. The question is what's the name of it? Once I know what it's called, then I can look into finding out it's respective part #, so that I can buy it.

Thank You!

When splicing double flared brake lines with the suitable fittings and when splicing fuel lines with compression fittings, how tight are they supposed to be tightened? A 1/4 turn, 1/2 a turn, a full revolution turns or until all the threads are screwed in?

Thank you!