Since disc brakes require substantialy more apply power, as they became popular in the mid 60s, brake boosters became almost mandatory. Front drums were a thing of the past by 1970. They did, however outlive the 'single circuit brake system'. If you share the road with other cars or pedestrians, please upgrade to a 'dual circuit system' It might save your shiny bumper someday, I've seen some way too nice cars hit the wall when one little rubber peice failed.