Remove the brake lines from the side of the master cylinder assembly.
Remove the two nuts and bracket from the 2 master cylinder mounting studs.
Remove the vacuum hose from the vacuum hose port.
Remove brake master cylinder.
Disconnect brake pedal linkage inside cab and mounting bolts.
Remove vacuum brake booster.
Re-assemble in reverse order. Bleed the lines at the master cylinder. Test operation.
To test a vacuum brake booster, pump the brake pedal several times with the vehicle's engine off. Apply pressure to the brake pedal and then start the engine. The brake pedal should move downward about one inch (25mm).