Had the same problem about 2 months ago. Although I didn't want to mess with the repair myself, the wonderful dealer network in this area absolutely refused to drain the fuel tank prior to lowering it. It seems the wonderful N. Va dealers (and I called most of them within 30 miles) would only drain gasoline, not diesel. I was repeatedly told to bring the vehicle in with the tank empty (I had just topped off prior to the brake line splitting). As I didn't have any place to temporarily store ~34 gallons of diesel, I fitted a new 3/16" brake line to the rear axle using pre-flared lengths of tubing from a local Napa store and two unions. Doing this in 33 degree freezing rain was a terrific experience, though I suppose better than were it -20 (F).
With the brakes now repaired, I am planning to replace all the brake line, front and rear this summer with SS 3/16" line and fittings from Inline Tube.
While the tank is down, I also will replace both the fuel feed & return lines as well, since I noticed they are both very badly rusted. That's another problem waiting to happen.