Well interestingly enough that is exactly what I ended up having to do. The part Ford kept ordering was the wrong one, and it took them 3 days to figure out that the brake line is no longer made.
It took me another 3 days to create a good line from scratch to replace the exsisting line. I got a pipe cutter, pipe bender, and double flare tool from Harbor Freight.
One of the challanges with making the line is that one side was a bubble flare and the other was a double flare and there were (2) different bolt fittings too, so finding one at NAPA or anywhere else exatly was not happening.
What I did was get the fittings I needed 1st from different lengths sold and cut them to take off the fittings. Then I used a line that had a bubble flare on each end and cut off one end. I then slipped on the appropriate fittings and created a double flare on the cut off end. Getting that double flare right was not easy. I must have done about 25 flares (test and not) before I got one I felt mostly comfortable putting on the car. Then I re-bent the line and put it back on the car. I mage a
lot of rookie mistakes.
I have bled the system and driven the car about 50 miles with no problems. I thought about getting this line from a junkyard to have a back-up but I only found 1 out in Oregon, and the guy wanted $50!
My line should be good to go. This is a good thing to note for other Mustang owners; if one of those lines needs replaced there will probably be no ordering them new from the dealer. You will have to make one or have it made for you.

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2000 Ford Mustang V6 - 5 Speed
Front to Back Upgrades Exterior: K&N Filtercharger, MSD 8.5mm Wires, MAC Ceramic Shortie Headers, Pacesetter dual exhaust adapter, True Dual Flowmaster Force II exhaust.
Front to Back Interior Upgrades: AutoMeter Lunar gauges, Razo RP55 pedals, Razo RA9 shifter, tinted windows, LED brake light.
Suspension/Brakes/Wheels: 17X9&17x10 Shelby Torq-Thrust M Black wheels, Kumho Ecsta ASX 245/45ZR17(F) 275/40ZR17(R), Brembo Slotted Rotors, Hawk HPS Pads, Russell SS Lines.