The 70 series (heavy duty iterations) went to the same birfields as the 80 series at the same time. There is logic in what Toyota did across the wagons and the heavy duty 7x series trucks.
Then, in 1998, 7x series trucks went to the 10mm hub studs, front and rear, just like the 100/105 series...
100% weight savings and less NVH and more robust reliability paired with available power trains. All of the 70 series trucks went to the same setup as well At roughly the same time (phased in by market and platform).
Toyota knows what they are doing.