I spent too much time on this, and I think I have things finally figured out.
Turns out the blades on my truck are not the originals, but a "universal" fit sold at a Toyota dealer. I went and had a chat with a parts guy, showed him one of the blades, and he said "oh no way that is a factory blade, that's a generic replacement that we sell". Did some more searching, and here is what I found:
Original factory blades that came on these trucks:
Left (driver) side: 85222-42110, length is 600mm, right on the box.
Rights (passenger) side: 85222-53071, length is 550mm, right on the box.
These blades are made in Japan, are very high quality, and include new inserts. They have a profile that uses the airflow to force them down on the windshield. I ordered a pair from McGeorge Toyota, they were $20.31 each (not including shipping). The mounting part of the blade looks like this, if you want to compare with yours:
Versus the blades that were on my truck when I bought it, I saw the logo and assumed they were original:
The inserts that beno provided the part numbers for fit these blades perfectly. But dealers do not want to stock them or even order them, as they have to order 10 of them, and then they get stuck with them. Nobody buys inserts anymore, they just buy new blades.