NBT,
I think it is the date code. Carter 4bbls generally were sequential with their numbering system. That jetting info I listed earlier comes from a 1971 Street & Strip annual that I have kept all these years, so I believe that those Comp Series would have been fairly new at that time.
Long boosters. Carter made 505 versions of the AFB, majority were production carbs. Some had long boosters, some had short boosters; some had the the booster leg pointing upwards, some had the leg pointing downwards. The up/down location of the venturi restriction was adjusted accordingly. Each carb was essentially custom designed for each engine. One of the sales 'features' of the Edel AFBs is the bullet nose on the pri booster nozzle. The Carter AFB on my 66 GTO had those.....
