Thank you!

 

Did you follow it? where does it start and end?
Could be a brake line of an E-brake cable.

 

it starts up front somewhere, I can’t actually follow it without getting the car off the ground.

E brake has the hard line I believe that’s still intact. I am not sure, though.

 

I just saw this replacing my fuel filter yesterday. It seems to run down the inside of the driver frame rail, just beneath the fuel filter. Definitely not the E-brake cable. Mine's not quite as corroded as that, but close. I'm curious too what this is.

 

Everything seems to work fine without it.. Hopefully somebody recognizes what it is and chimes in!

 

I bet it's an abandoned brake (fluid) line.
See if the brake lines are new...possibly plastic.