Hi Alex.

Is the car predominantly driven in 2wd or 4wd? To me it does not sound like gearbox. I think you have a stuffed free wheeling hub. Are your front hubs Manual? I think they will be as the auto hubs were on later GQs but not sire in your country. If you have Auto hubs then I'd be 99% certain it's a hub.

Try and drive with the windows down and see if you xan isolate it to the front and to what side. If it's gearbox you should be able to determine and isolate it to the centre of the car.

Second guess for me would be front diff centre buy if it's not doing it in 2 wd then maybe not.