Just for the addition of general knowledge, and not particularly related to this application (haven't torn the brake system down on that type of truck) I'll share an experience I had with an old Mazda B2000 I had. I was using it to move back from Iowa one time and I knew the brakes were a bit squishy, but figured it would manage until I got home. <img src="/forums/images/graemlins/shame.gif" alt="" /> Coming up on stopped traffic on the highway, pedal went down and brakes did little to nothing. My mother (driving) ended up scooting down the median with the emergency brake locked up and passing about 4 cars. <img src="/forums/images/graemlins/shocked.gif" alt="" /> We got a round of applause, cleaned ourselves, and limped it the rest of the way home.

The culprit we found was one of the pins that the caliper slid on to compress the pads. During the previos winter it had seen sufficient high snow and salt that there had actually grown a rust ring which siezed one pin. The end result was it was torqueing my caliper in order to make contact with only about half the pad. Eventually we got into a high load situation and the caliper couldn't bend far enough to deliver stopping power. It was exciting. A simple fix, but could have sure messed up my world.

As I said, I don't think this applies particularly to your truck, but the conceptmay have some application.
$.02
James