the weirdest brake line failure I had was while sitting still. was at the local county fair, july 4th after the fireworks, had the ‘93. I was sitting in in before my daughter and (now ex) wife got in, engine idling, a/c on. had my foot on the pedal just enough to hold the truck as I was on a slight hill. (no parking brake, I carry a small supply of 2x4 wood blocks) well the brake pedal starts dropping, I didnt know if it was front or back and had all the stop & go traffic out of the fair and halfway home. turned out to be the line going to the rear axle. replaced it with mild steel line from the proportioning valve all the way to the back where the flex hose hooks up. yes, double flare. Never had any other rear brake issues. 3 years later was replacing front pads and when I was pushing the pedal in driveway to seat the caliper pistons and get the firm pedal, the line crossing from left wheel to right wheel went out. So I replaced everything on front, flex hoses and all. Id of hated to of been pulling a trailer and that happen, esp with the front brakes.