Yes, I also think it would be the W56, but the ID plate is confusing me
If this is a 21 or 23 spline W56 gearbox, the only solution for crawler gears will then be to replace the 2,28:1 with a 4,0 or 4,7 gears and since this is forward shift, I do not have the possiblity for a dual case, if I understandf correctly ?
The 5.13 gears are some original Toyota parts, but here in Norway they will charge about 1.000,- USD each set !!!!
Since I still have the IFS up front, I have one set 7,5" up front and one 8" in the rear, both taken form the scrapped 1987 Hiace 4x4 van. Nobody buy these new, those who use them are taking them from scrapped cars. Both 7,5" and 8" do have 8/41 teeth on the P/R.
A lot of "hardcore" offroaders here in Norway claim the best gearing is the 4,88 with 8/39 teeth and that the 5,29 with 7/37 teeth are too week, not to talk about the 5,71 gearing... Therefor the 5,13 would be just as strong as the 4,88 but still give lower gearing.