Nick, I know what toyota has to say about interchangability as I in a dealer, and I am one of toyotas youngest master techs. I recommend what I know to work, and with a complete change(no dex left) t4 will help the older a340es. to add to it I am looking at using a tundra tranny with standalone shift computer which runs t4 from the factory, and I have seen one of these take 500hp with only a upgraded cooler
Jared
Jared