There was an article in Australian muscle cars mag this year Im sure if you emailed them or got the hold of the mag there'd be a contact for a police historic vehicle association of some sort. Seem to have their own loyal band of enthusiasts as with,ambulances and hearses etc might even be able to help with bits. Id look up my mag but I have had trouble tracking them down since my bedside pile of car mags was declared an O H & S issue for the toddler!