Question: Is the Aisin tranny really $3,000 "better"?
I did a little more Google work, and think I answered my own question. The main thing people say about the Aisin is "It has PTO capability". From what I can see, "power take off" isn't really useful for hauling a 5'er since it seems to be some way to bleed off auxiliary power for other equipment, if I understand it correctly.
The other points about it seem to be more incremental, though it sounds like it does less "hunting" in hilly areas. In my mind, it's not $3,000 worth of better. One point a poster made was "you don't need a sledgehammer to drive in a nail". The 68F 6-speed automatic looks like a pretty solid tranny from the descriptions I've seen, and I see that it's predecessors had some serious problems from a reliability perspective.
Of course, looking at dealer inventories, they all seem to be loaded up with the Aisin, which is another good reason to factory order; don't want what I don't need.
Then, again, there's nothing like personal experiences, so I don't consider the subject closed if y'all don't. :)