Bosch Hydro-boost is used by OEMS where engine vacuum is not sufficient to support a vacuum booster (like a diesel engine). Or the braking demands exceed the capability of a vacuum booster. These are some vehicles that come from the factory with Hydro-boost: Ford F-250/F-350 pickups with diesel engine, F-450/F-550. Ford Mustang Cobra. Chevy 2500/3500HD with diesel. Buick LeSabre with diesel engine. On these vehicles the power steering pump supplies the hydraulic brake booster and the steering gear.
They were also used on the '84 Turbo Regals. Unfortunately, they tend to leak due to the weight of the assembly. With a cast iron master cylinder on the end of the cast iron Hydro-Boost unit, the whole thing is well over a foot long! All this weight bouncing up and down while the car is moving really plays havock with the base seal. Most guys end up switching to vacuum brakes.
