Maybe 24/P's are cheaper to make?
Mike, maybe they plan to put the 24's on a smaller chassis, because the 34 chassis are too big?
I agree with LtDan that especially in the Adelaide hills, 34's can be too big to fit up the driveways and with the length of some hills driveways, leaving the truck on the road and running hose down, isn't practical, especially for rural fires.