I have a 1974 chevy C10 stepside. I couple of years ago I went through the brakes and replaced calipers, wheel cylinders, master cylinder, vacuum booster, vacuum booster hose, proportioning valve, and the y fitting in the rear that distributes from the rear single line to the two rear wheel cylinders. Brakes were great, then suddenly a couple of months ago the pedal went clear to the top and the rear brakes started coming on before the fronts, (which makes a hard stop a bit of a carnival ride). Also the brakes would stick on and not release for a few seconds after I took my foot off of the pedal. Long story short, the front brake hoses had become so narrowed inside that the fluid was slowed going in and going out. (were they 49 years old??) Replaced the hoses and good to go again. Just sharing some experience..... thanks for all you guys have taught me so far!!