I have been assured (by my independent toyota mechanic) that these manual hubs are the originals. So changing back is not a possibility.
If a bit of gas mileage is the only downside to leaving the hubs locked, I can live with that. I was worried about wearing them out.
Why do you say you should “only uses 4 wheel drive when needed”? what problems does it cause if I over use 4 wheeel drive?