HQ chassis number meaning

[Innuendo]

September is the model year change point. So 10th Month is the new model with Holden and 9th month the last of the previous. I.E: 9th month 1974 is a HQ 10th month 1974 is a HJ this is true in "most" cases. Sometimes certain commercial model Holden's would carry pass the date. Although not in HQ-WB.

ADR updates are the reason for the letter prefix change in chassis numbers. That's not to say when a ADR is introduced but from when it is introduced to that model. Holden would sometimes introduce the change before the fact in preparation.

[Rustyhq]

Thanks for all the answers everyone I have been sitting back reading all the posts and learning. Definitely glad I stumbled across this site. Full of many helpful people. Cheers