Once the parts came in, I started in on rebuilding the calipers. The back seals and pistons were not to bad when I opened them up. The calipers all had stainless steel inserts so they had likely been rebuilt before. I started with the two back calipers and took time to clean them inside with a bit of brake fluid. I replaced the springs and cleaned up the existing pistons as much as possible. In the case where the piston was well worn, I replaced it with a new piston. I then replaced the seal as well. I repeated the process on all four halves of the back calipers, got them mounted back on the rotor and them moved on the front.
When I cracked the front calipers open, I was surprised to see a complete mess. The pistons were jammed and there was a white sand like substance all over the inside of the caliper. This could be the reason that we did not get braked fluid through the front lines when we tried bleeding them. I pulled the seals off and began the process of cleaning up the caliper, replacing the springs, pistons and seals. After the cleanup, I got the front calipers mounted back on the rotors. With everything functioning as it should, I was ready to start replacing the caliper lines and reconnecting the brake system, the last piece would be bench bleeding the master cylinder before bleeding the brakes.