Another possible origin of the tem “86” can be attributed to the United States Navy.
It seems they used something called an “allowance type” (AT) aboard warships that indicated why certain parts were being kept in stock. Since many of the parts were either subject to upgrades, replacement or had become obsolete they were each assigned what was known as an “AT” code.
After World War II was over many of the ships in the fleet were either decommissioned, sold off for scrap or simply mothballed until the Navy could determine what to do with them. While they were dry docked, workers aboard the ship would take an inventory of the spare parts and those that could be discarded or were no longer useful were given the term AT-6 and the term has since become synonymous with throwing something away or discarding it entirely.