I do believe I have an issue with my hydroboost system, maybe, well we'll see. Unit was replaced roughly 8 years ago when peddle went to the floor and had zero and I mean zero brakes. Fast forward to 2 weeks ago, pedal went almost to the floor again. Checked brake fluid and rear reservoir was almost empty. Filled and checked for leaks and found none. Brakes returned to near normal with some intermittent pedal bounce. This past 4th while pulling a car in a parade the pedal went to the floor and had maybe 10% brakes. Enough to finish the parade and get home with lots of down shifting and long slow stops. Checked all fluids and they are full. No leaks. However while driving before the parade and slowing down for a turn the brake pedal got hard, very hard to push and the steering almost refused to turn. Almost like when you an engine cuts out and you lose everything. It came back after several seconds and was fine until it fully failed. I find that symptom very odd. Best guess that the booster went out again. But could it be the ps pump? Although steering is fine at this point. Pedal will not pump up when not running either, won't build pressure. Just looking for ideas before I dish out the money for a new booster and labor. This is on an '89 (most parts are 87 which is why I am here) R3500, dually crew.