People sometimes ask about how to determine which rear end their came with, and the list of options on that one is surprisingly limited. Here is that list of axle codes with their gear ratios correlated with engine code. There was a limited slip version of all of these rear ends, which had a different code, but, those were extremely rare in all but the 9 inch rear end used exclusively in the K codes.
U/3.50/5
F/3.00/1
D/3.00/1
K( on 64 1/2s) 3.89/8 or 4.11/9
T(with manual tranny) 3.20/3
T (with automatic tranny) 2.83/2
C/2.80/6
A/3.00/1
K (on 65s)3.50/5, 3.89/ 8 or 4.11/9
K(on 66s) same as 65, except the limited slip 3.50 gear had a code of E, and the 4.11 was no longer available.