I am going to make an assumption here and think out loud (or in type) and ask the question to your question “could this right hand slider be punched for right hand drive burbs and the holes are just not used on all are lefty drive burbs. I’ll see if I have and aussie fellas that could send me some pics.

I have seen many front burb seats (three of my own) and none that I have seen have any type of rod going across to the right side or any type of lock or latch on the right side adjuster.
Mike