Quite often when introducing new parts for ADR compliance, it can be done way ahead depending on existing stocks of the necessary parts at the time. There are many cases in Holden production where ADR items were introduced into production ahead of the required legal date. They could have exhausted the stocks of 5mm steering wheels in say Sept 1977 & began fitting 3mm wheels 5 months ahead of time, yet these cars would have still remained legal.
Also AFAIK the ADR25a intro date was Feb 78 (not Jan), at that time AHZ became BHX & CLX became DLX.
Dr Terry
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