Hydra boost? hyd pressure instead of vacuum?? Yes I have the one that came out of the bread truck, Same set up that's in one ton chevys. They work so good you can lock all 4 tires with your big toe, had to modify the pedal where the rod hooks to it and I reinforced the firewall and droped a support down to a lower position on the firewall.
83 cj8 4BTAA cummins, NV4500, clocked dana 300, 3.55 gears 35 inch cooper stt, EXCELLENT FUEL MILEAGE.