how hard is it to change the oil in the front and rear diff? what kind of oil do you use regular gear oil or is there a special kind also would this be a good time to change the transfer case oil if so how hard is it?

 

You need a 24mm socket. Remove the fill bolts first to make sure you'll get new gear oil in. If they come off then remove the drain bolts. You will get 2.3 qts in the rear and 2.0 in the front or thereabouts (I think the 3rd gens use slightly different amounts than my 2nd gen.)

Use a synthetic gear oil - mobil 1 75w90 is about $9 a quart. Your diff gears will run cooler and sunthetic lasts a lot longer.

 

http://www.top4runners.com/ja/synthetic.html

 

I recommend you buy a cheap hand pump at an auto parts store. Pour the oil in a clean gallon milk jug and use the pump. Makes the job much easier. Having an assistant also helps. I use Mobil 1 75W-90 and also replaced the gaskets.

It's all covered in the web page that data referenced.