I am in process of gathering materials to do the same thing. From what I read, it's a straight forward drain and fill. After double checking the owner's manual for oil type (I am glad I did) I found that the transfer case/TOD uses Dexron III and not gear lube as I assumed Would have been an expensive mistake! Anyway, I am really not sure where the drain and fill plugs are on the TOD until I get under and look for them. The axle diffs are pretty straight forward, rear has visible drain plug and the front uses the bottom most cover bolt for a drain.