So the sticker here is that the gearing was tested by turning the tire and counting the shaft revolutions. But there's enough question about how this is happening, that I would think revisiting the gear test would be a good thing at this point.
At least you can confirm your first test results were correct, but better yet would be to find out they were wrong and you do in fact have 4.56 gears.
Would be nicer than a trans rebuild at this point!
Even with that as an option, I would think it would be the last straw. Not because it sounds implausible, but because in all these years I've never heard of that happening with any transmission!
Anybody else ever heard of a transmission slipping that much?
Paul