I have a 64 C10 with a completely stock braking system. I went through the entire braking system, and rebuilt everything, the self adjusters are clean, straight, oiled, and spin freely. The wheel cylinders were all replaced along with the master cylinder, a few hard and soft lines, and anything else that was suspect. I replaced everything with UP or other fairly high quality parts. Pretty standard stuff. Not many miles after the initial replacement of everything the left rear brake started dragging. I found that the wheel cylinder had went, and was locked open. I replaced it with a Wagner unit. I felt a drag on the way home last night, and when I got home I touched all the hubs. Guess which wheel was hot.... left rear feels like it has a hung up brake again, and I'm guessing it's the wheel cylinder. I checked the self adjuster thoroughly after the last time, it's functioning well. It is the last wheel cylinder in line. I'm wondering if that has anything to do with it giving up. Any ideas or suggestions?