There is one L34 that was reportedly resprayed in the factory. It was a very late build (Sept) and the owner liked the new Mandarin colour rather than the Salamanca the body was painted in. I think the car was already assembled, but they mostly took it apart again for the respray. This is all hearsay of course.
I think you'll find it also includes Chinese Whispers! To paint a car in the body plant the whole car would need to be stripped back to nothing as they are heated in an oven, and then put back in to bake the paint as it wasn't air dry Acrylic. It was heat cured.
If it was resprayed at GMH it would have been done by an outside contractor or possibly in another area, like wherever they sprayed the front panels at Dandendong for the van and cab-chassis bodies that came from Elizabeth already painted including doors.
It also couldn't have couldn't have been done at Dandenong in the BAP as Dandenong were using HQ colours way past the start of HJ restricted production but only for Torana plus Glacier on HJ utes. GMH didn't want any HJ in HQ colours (except Dandenong utes) so changed over to the HJ colours early like August and September. All remaining HQ paint was sent to Dandenong to use on LH Torana. I believe some colours even lasted until November.