The original Vacuum Reservoir is a welded off section of the frame in front of the passenger footwell. If you have a separate vacuum can (sometimes they are round like a ball about 8" in diameter or like a large metal coffee can) than your frame one is most likely toast too. Just install a new one where the old one was.

The reservoir allows the brakes to function with power for a few pumps even if the engine stalls. Trust me you need one!