On my 92 D250 the brakes are acting up. The pedal goes close to the floor, doesn't touch the floor, but you need to push very hard to get the brakes to work. It won't skid till you pump it up a lot of times then it acts normal and the pedal works normal without going near the floor. The front reservour in the master cylinder was 2/3rds low but, not much for leaks anywhere that I can see. The right rear has dust sticking to the rim near the rim holes but that's been there awhile.The vacuum booster has good hoses and clamps as far as I can tell......Any help is appreciated. It's my much needed work truck.T.I.A.

Time to go over the hydraulic system with a fine tooth comb. Check callipers and wheel cylinders for damage or leakage. Brake hoses for damage. Disassemble and clean both callipers and whell cylinders. Check everything for proper fit and for pitting / rusting.

orings in the plunger letting pressure flow past?

As soon as we got the brakes fixed the steering gear box bracket broke. Now I'll be on my third one. Going to try and reinforce it somehow for the time being.