[CTBob]

Hey, Steve!

Chrysler uses a finite-but-numerous variety of date coding scenarios, in combination, or, alone. Some use the letters exactly as you have listed. Others use numerals:
1-January
2-February
3-March
4-April
5-May
6-June
7-July
8-August
9-September
10-October
11-November
12-December

SPDs (Scheduled Production Dates) use:
1-January
2-February
3-March
4-April
5-May
6-June
7-July
8-August
9-September
A-October
B-November
C-December

I know that Dana rear ends list numerical dates on the axle tubes (i.e.: 4 15 70 = April 15, 1970), but, having not had a car with an 8-¾" in a while, I'm not absolutely certain what the casting date protocol for the carrier assembly is. (Further research may turn up an answer, or, perhaps, someone on the Forum may know!) That's why I said "MAY," and, "truly tentative." It would seem logical that that first character should be a numeral, and, not a letter. I put "C" because that's what it appeared to be to me in the photo, as well as I could ascertain.

Month/Year date codes, as you mentioned, re: the jack, are definitely common, so as you stated "C 0" (or, 0 C?) is March 1970! Perfect! …But, usually, they appear as in you example. I don't recall having seen any Alpha/Numeric (such as "C 0") utilized in lengthier ways (such as "C 9 70"), which is why I went "out on a limb" (axle tube?), so to speak, and, translated it into the "other" alpha possibility. If you are able to tell what that first character is, we may arrive at a better (and, more accurate) answer.

…And, that's so great about Terry! Not only is he able to help you, but, he still has the '71 'Cuda! Fantastic memories from back in the day! So cool!