Installation Procedure

Inspect the reservoir for cracks or deformation. If found, replace the reservoir.
Clean the reservoir with denatured alcohol, or equivalent.
Dry the reservoir with non-lubricated, filtered air.
Lubricate the new seals and the outer surface area of the reservoir-to-housing barrels with Delco Supreme 11® GM P/N 12377967 (Canadian P/N 992667) or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.

Fig 1: View Of Master Cylinder Seals

Courtesy of GENERAL MOTORS CORP.

Insert the O-rings into the grooves in the reservoir. Make sure that the O-rings are properly seated.
Install the reservoir to the master cylinder body. Use your hand in order to press the reservoir straight down into the body.
Install the master cylinder. Refer to Master Cylinder Replacement in Hydraulic Brakes.