I have rebuilt on a set of K-H brakes this winter. They had been mounted on a 67 Dart, never dismounted. It took me a week just to get the calipers apart (a lot of penetrating oil was needed), where after the challenge was to get the pistons out. I used compressed air, it worked but was not exactly harmlessly. Pistons came with high speed when they released. I bought four new pistons and a complete set of gaskets from Rock Auto. Four pistons were ok, these I kept. I honed and assembled the calipers. The short brake lines, sitting on the calipers were rejected, I bent new by myself. Have driven the car with my KH disc brakes for three months, is 100% satisfied.