I don't think This is an export wagon, it is the prototype wagon in disguise as an Opel for road testing. There are lots of photos of it in various Holden books along with the sedan. According to my research there were 4 sedans and 2 wagons made, all black, and all badged the same way which were used for testing. And yes the wagons were made at the same time as the sedans but not released until later.
The FEFC club used to meet at the same place as the Holden retires club and we had some fruitful discussions with them.
Ken
Hi John, I found these pictures hope they help.
Cheers Stewy