The single piston calipers have only ONE piston, it's on the inside of the rotor. The caliper kinda looks like a c-clamp.MaryBeth the single piston caliper will have only one big piston on each side of the roter that the pads go against. Take a pic if you can't tell.
I believe they are referring to the single brake line going to the rear of the body, the interconnecting line from the proportioning valve to the rubber hose at the rear axle.One more question. I see listings for 1 pc and 2 pc lines. What is the difference, other than the 1 pc has to be bent for shipping if it is ordered and not purchased locally.