I have 4 holley choke covers/cap with their assemblies. They have 57M1, 58L1, 57M2 and 58L2 indicated in the center of the choke cap. What do these numbers/letters mean? They have either red, black or white plastic cams on the backside. Which of these will work on a very 383 dated, early 1964, 2818 holley for 365 hsp???