GMH did build floor shift aussie 3spd boxes, but as far as I know these only ever existed in CF Bedfords. They were not an option on HK-WB. You can easily do it yourself if you want by using an aussie 4spd extension housing and shifter on an aussie 3psd. It will all fit and work as per a 4spd except the shift pattern is Rev top left, 1st bottom left, 2nd top right, 3rd bottom right. Plus there will be no reverse switch.