Thanks M60A3Driver

Small update. I've managed to talk today to the original owner (NZ is a small country!), who worked for the Chrysler franchise in NZ. It was his work car. He bought it back a few years later and did the tune himself through Eurocharge. He may have the original file (or Eurocharge might?).

Bonus: he has kept track of the car through its life so have given me its full history - which also explains its extraordinarily good condition.