this is for later years but may still apply
Some customers may comment on a squeak noise when the brake pedal is applied or when released. This noise is normally heard when the brake pedal is slowly applied with the engine on or off, but can occur when the brake pedal is released. The noise may be isolated to the master cylinder area.
Correction
To correct this concern, remove as much of the old brake fluid from the master cylinder as possible and refill with a new DOT 3 brake fluid, P/N 88862806 (in Canada, use P/N 88862807). Start the vehicle and fully cycle the brake pedal until the noise diminishes to allow the new fluid to enter the system.