Do you have access to a service manual for your truck? The big rigs have somewhat different brake systems than the pickups, and I'm not sure what a 51 2-ton would have as an adjustment procedure, or even what design brake system you've got. Bendix-type brakes have a single star wheel adjuster at the bottom of the backing plate, Lockheed brakes have two hex head cams resembling bolt heads at the midpoint of the backing plate, and Huck brakes have a star wheel surrounding the ends of the wheel cylinders at the top. Each system has different adjusting procedures, but they all involve getting the brake shoes snug against the brake drum, and then backing off just far enough to let the drum turn freely without creating an excessive amount of pedal stroke. One of the big rig guys will be along shortly with more specific information and/or a service manual reference.
It might be a good idea to start a thread in the "Big Bolts" forum asking specific questions about adjusting your brakes.
Jerry
