Remove the suspect, or better yet, all the lines carefully, blow the old fluid into a jug for proper disposal, then bend and flare clones of the original tubing runs. Otherwise, you can buy a set of pre-bent lines. One thing will doubtless lead to another, most of the old hoses and lines probably should be replaced. But that is better than bashing into an expensive imported car and paying to fix it and the owners chiropractor bills. If you are on a budget, you could do a piece at a time, but most would say better to make it all right than gamble on old corroded steel lines and rotten hoses.
I've swapped out the old single shot master cylinders for modern dual masters, so I bought good quality tubing benders and double lap flare tools so I could make my own lines. Your time, or your money, your choice. At least the tools will be there for the fuel lines and the next truck.
