hydro- boost brake using g-m astro unit

pishta said
This is what I skimmed over looking for Prop valve specs...maybe its been adapted...

"Hydrovac was a common early add on for original single circuit brake system
They work well, but only for single circuit brake systems. Modern VH44 equivalents are cheap on ebay."

Hydro Boost With Hanging Pedals

No He's referring to HydroVAC which is an entirely different animal. The way they work(ed) is, they are vacuum like a vacuum booster, but some have TWO separate hydraulic circuits. They have a slave end which the master drives, and this acuates the booster, and then an output hydraulic side, which of course goes to the brakes. These were used in older mid size trucks, and were once a "handy" add-on for things like old Jeeps

One type here