Jimmy,
I have a few thoughts/questions;
1... are you still using the original MC or has it been replaced? It should have an 1-1/4" bore with casting number 5450259.
2... pumping the pedal to make it hard can be caused by the shoes being to far away from the drums requiring more fluid at the wheel cylinders than one push can deliver. Jack the truck up one wheel at a time and see if you have resistance when turning the wheel by hand...you want some resistance. Now that you've driven the truck the shoes should be centered in the drums.
3... did you replace ALL of the rubber lines? If not they can swell up internally and act like a check valve delaying the flow of fluid back to the MC.
Mike B
