With the 35's I'd suggest 4.56 gears.
Here's a good site to get them from.
Auto Parts - Differentials. AMC,Chrysler,Dana Spicer,Ford,GM,Suzuki,Toyota,
Go with the Yukon brand.
You'll also have to an install kit for each differential.
Also contact a local drive line/gear shop to see how much they would charge for parts and labor or just labor.
Changing gears isn't for the amatures or novice weekend wrench turners.