My 69 chevelle sat in the garage all winter and when I pulled it out NO BRAKES! I had noticed that the the rear resevoir was empty it had leaked out between the maaster cyclinder and the power booster. Can anyone tell me what to do or what to replace?

thanks

replace the master cylinder. What you experienced is not unusual. Be sure to bench bleed the master cylinder before installation. It cannot be properly bled on the car because it is tilted up at the front. Bench bleed it level in a vice.