Guys... really.... Holden didn't keep using silver GTS dashes up after the change.... you don't see HZ's with silver GTS dashes in them because... hey... we have heaps left over so lets use them up.... seriously... Holden like any other company had strict quality control checks.... not to mention parts accountability... each Holden plant would have a standing order with outside suppliers and would has shipped in what they needed on a weekly basis, they wouldn't have the space to stockpile huge quantities of parts for all the models being manufactured.

not to mention the need to supply parts to the Nation wide dealer network, any left over parts would be sent to dealers for spares and once they ran out would be superceded by the replacement part. I remember going in to Holden in 1981 for a silver GTS dash to replace a broken one in my HX Sandman, the only ones available were the base model flat black ones seen in WB. You couldn't even get a HZ black chrome one.

Most dealers today don't even stock spare parts at all, they order them in as needed from the manufacturer who in turn orders them from the supplier.