Brake Hoses, Lines/piping, And Fittings problems of the 2012 GMC Sierra

At 81,000, miles the rear steel brake line from the frame to the rear end rusted out and burst. At 83000, miles 3 of the steel brake lines, located under the drivers door area at the left frame rail in a bundle of 6 lines, rusted out and burst. Luckily I was able to stop my truck each time by use of the parking brake and did not crash. All the steel brake lines are rusted very badly and need replacing. My local dealer quoted me $2270. 00 dollars to replace all the lines.