I realize this thread is really old but thought I would share my experience. I purchased stainless brake lines and could not get them to stop leaking so I replaced the stainless lines with steel and no more leaks. I also installed new front calipers, brake lines, a new brake booster and master cylinder. The car is a 71 Barracuda with 4 wheel disc brakes (rear brake calipers and rotors from Dr Diff on a Dana 60 with no problems). Dr Diff said use the proportioning valve for 4 wheel drum brakes and my 4 wheel disc brakes work great (no leaks, hard brake pedal, car stops straight). I will never use stainless brake line again! I could not stop the leaks!