swapping out ring and pinion 7 1/4

Well, casting numbers aren't part numbers, but they're often close. Here are the A-body 7-1/4" housing P/Ns:

'63: 2404 073
'65: 2467 414
'67, 69: 2800 443
'70, '71: 3432 647
'72: 3432 647 "Without adjustor-type axle"
'72: 3683 958 "With adjustor-type axle"
'73, '74: 3683 958