As above Holden today have little idea what GMH were doing back then, and are of liitle to no help. I'd be surprised if it isn't a Sandman. It is a 5.0L example, or at least the tags were off a 5.0L example. VIN and BODY numbers pretty much align, i'd have to see the build date and chassis numbers to tell you if that ID plate belongs to the others. TRIM line off the body plate will help too, it is probably 60A but could also be 18V.