SL hatches had the silver trim around the tail lights and so the panel had holes for the trim's pins to insert:
Thread on the trims here: http://www.gmh-toran...-mounting-lugs/
Photo of trim in place below:
Not sure about Sunbird hatch having these but SS variants didn't have this trim or holes.
The QLD Torana Club says Sunbird hatch was not released until mid 1977 which is right around Bigfella's estimated build time of you car: http://www.qtcc.org.au/lx_specs.php
Might be something to check to get you on the scent (assuming the rear valance hasn't been replaced at some stage).
Cheers, TB
Edited by Tyre biter, 25 September 2016 - 07:59 AM.