Can anyone tell me what would be the correct power brake booster for my 67 Camaro SS 350. Should it have a "DELCO MORAINE" stamp on the upper left hand side of the front of the booster? Also, should the "O"s be open on the sides? I've seen them stamped both way. With the "O" openen on the sides, and also with closed "O"s. Which is correct?