Since it looks like we are just guessing on the stampings on the tag (especially the serial "number", which is not a production number), here is my guess (based on an Internet search and a look at a few tags):
Delco ID Plate - 12v example (12v = red tag; 6v = black tag)
Left code is the Model ID - some numbers are given above
Right code is the Serial ("number/code"), which appears to be a date code (a web search confirms this).
Year | Month | Day
7 A 15
7 = 57
A = January
15 = 15th of the month
Here is a 6v tag on a 1954 6v generator Serial ("code/number"):
Year | Month | Day
4 D 9
4 = 1954
D = April
9 = 9th day
Supposedly, for 1953 and newer, the month code "I" was skipped (so, September was "J" and December was "M").
Pick a date that suits you (birthday, or maybe a date that year that is of historical significance; or, a date near the starter or distributor dates, if they have tags).
