4 speed numbers

On the subject of numbers, I know how to read the pad stamped codes. However, I have a late model A833OD with the numbers pp833 2400 stamped on the pad and no 8-digit partial VIN. But it wasn't built on February 22nd, 1968. It is a post-1975 OD transmission, possibly from a truck. The longtail has "6-2-80" stamped/molded into it and the front of the case has "8B 4 80" stamped/molded into it. It is the OD with the 5.125" retainer & 308 as well.

In any case, I know what I've got. I even went in and counted gear teeth etc. to verify exactly what I have. I'm just offering this info because it appears somewhere along the line, MOPAR changed the calendar dating process/sequencing for the A833. I think I read somewhere that the new calendar started on Dec 14th, 1988 because the old one ended Dec 13th, 1988. Can anyone verify this, at least for the A833OD?