During the last couple years, I've been trying to catagorize, differentiate, and classify Craftsman teardrop style ratchets manufactured between approximately 1956 and 1993. I think I've finally identified every "type" / iteration that exists for drive sizes 1/2", 3/8" and 1/4". I have just about every iteration, in all three drive sizes, with the exception of just a few that I'm still looking for. I see dozens of Craftsman teardrop ratchets on eBay EVERY day. I'm pretty familiar with these particular ratchets.
While I could be wrong, I think the ratchet depicted in your post was most likely manufactured during the early 1980s. Those letter codes you're referring to actually started showing up in all three drive sizes (1/2, 3/8, 1/4) two "types" or iterations before the ratchet in your post, and continued one type/iteration after your ratchet. The first 1/2" drive ratchet with the letter in the recess was model number 44975 with manufacturer code -VV-. The letters in the retainer ring recess differ from example to example. I've seen letters A through L on the 1/2" drives, as well as 3/8" and 1/4". There could be more, but those are the only 12 letters I've seen. My best guess is that the letters MAY represent the factory of manufacture, or assembly line, or work shift, or forge, however, since there are only 12 letters observed, and 12 months in a year, the letters might represent the month a ratchet was produced. (A = January, B = February, etc.) I've seen this type of letter code arrangement on old car parts and machine parts. It could be true for ratchets too.
Jim C.