Unfortunately that doesn't appy to any Holden vehicle prior to VN Commodore as they were the first models to get a ISOVIN number. The skinny tag on your HQ, HJ, HX, HZ etc is not a VIN number perse'. In our old cars the chassis number is the vehicle identification and that is the number the transport dept. has recorded along the engine number it was last registered with.

The authentication letter from Holden isn't worth wiping your arse with let alone authenticating your Sandman, Monaro, XU1, A9X etc.

I know of several authentication letters from Holden stating the car has a M22 gearbox even though the body plate is clearly stamped M20????