what is this "research" thing you mention?

1971

383 manual - E & B-body
orange HP engine
---------- Holley R4667A ---------- part number 3512 848 on b'cast 48
383 manual - E & B-body - with "fresh air" (N96).
orange HP engine
---------- Holley R4734A ---------- part number 3512 849 on b'cast 49

***** some sources show the following manual trans carbs with the same part numbers (early/late/replacements) *****

383 manual - E & B-body
orange HP engine
---------- Holley R6191A ---------- part number 3512 848 on b'cast 48
383 manual - E & B-body - with "fresh air" (N96).
orange HP engine
---------- Holley R6193A ---------- part number 3512 849 on b'cast 49

383 automatic - C-body
blue engine
---------- Carter 6125S ---------- part number 3512 844 on b'cast 44

383 automatic - E & B-body
orange HP engine
---------- Holley R4668A ---------- part number 3512 830 on b'cast 30
383 automatic - E & B-body - with "fresh air" (N96).
orange HP engine
---------- Holley R4735A ---------- part number 3512 842 on b'cast 42