The biggest problem with these trucks is pads dragging because the calipers don't completely release. This can be helped by doing a very thorough cleaning, to the point of polishing, the surfaces the calipers slide on and use a silicon high temp brake grease to lube the surfaces and the pins.
Also, the rear drums don't self adjust very well, not at all actually, so manual adjustment should be done on a regular schedule, like at oil changes. This keeps from over working the fronts. After a rear adjustment you will have very strong braking, as time goes on you will start noticing slight pulling of the fronts, this means they are doing all the stopping and getting hot.
I went to EGR complete front and oversize cylinders on the rear. Haven't had any issues with brakes since as long as the rears are in adjustment. I clean and lube the fronts every spring.