Just some things that Tom Williams shared with me on the JPSK. Camillus lost the Government contract for these knives in 1984. The markings on your knife would have started showing up in 1885. The 89 date sounds correct for the 1219C2 fighting knife from Camillus.
After loosing the contract Camillus still assembled JPSK's with named and dated pommels for a period of time. I don't know for sure when this ended, but so far the latest dated Camillus I've run across is 3-1985. Camillus still sold the newer knives marked like the OP's example to AAFES for sale in the PX/BX system.