We were talking about this on the HQ Holden owners page on facebook and so far we have come up with these dates
for body colored firewalls.
Adelaide November 1973 to March 1974.
Brisbane October 1973 to June 1974.
Melbourne November 1973 to May 1974.
Sydney November 1973 to April 1974.
Interested in any feedback anyone may have on this one.
Cheers Paul.