Whilst I'm not 100%, I thought HJ introduced the new style radios. The following GMH film for HJ Premier and LS Monaro models show the new style radio that we see for HX (white numbers) and HZ (yellow numbers). There are a number of films showing HJ models which also show the same model (not like th HQ).



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Just an FYI, the above film was released in February 1975 so I'm guessing your Premier is a VERY early HJ.