One problem related to brake master cylinder has been reported for the 1996 GMC Safari. The most recently reported issues are listed below.
Applied brakes and system failed sporadicaly, most failures under dry condition on asphalt. Two brake modules, computer module, master cylinder, calipers, pads, rotors all been replaced. Front tires replaced at 24,000 miles. Pedal can be pressed to floor at any time, failure has a mushy pedal with a coasting to a stop. Some time making noise (unlike that of abs system) until pedal is released.