I've never seen enough of them to make a judgement. Some early ones (like the 7/77 pilot cars) had HX colours (I think the yellow one in the HZ Sandman brochure is Absinth), some saw HZ colours introduced early (like the Palais white ute on the brochure). HZ front suspension geometry started in 6/77. So as you can see some stuff changed early, some didn't until the series changeover.