Removal procedure:
- disconnect the vacuum booster pushrod from the pedal;
- unscrew the nuts securing the master cylinder to the booster, remove it from the studs and move it to the side;
- disconnect the hose from the amplifier;
- unscrew the nuts securing the vacuum booster to the front body panel and remove the booster.
Install the vacuum booster in reverse order.
(The article was borrowed from the website: chevyman)