The Model 10-7 was produced from 1977 to 1988.

The three-letter serial sequence patterns are notoriously out of whack, which is why there is no absolute cut-off, but a list in the SCSW of years when certain letter combinations have been documented. In the 4th Edition I can't find an ABS, but all AB combos seem to fall into 1983 or 1984, so that's most likely your ballpark.

PS: Correction, apparently a few AB's are known from 1982.

To quote the reassurance from the SCSW, "you may be able to make an educated guess from this, you may be completely wrong, good luck with that" .... Good to know they've got a sense of humor