transfercase/front/rear differential oils

[lowechj]

My 05 DC 4WD is coming due shortly to have the transfer case and front and rear differentials oils changed. The dealer wants close to $200.00 to do this so I was thinking of trying it myself. Can't be that difficult, I change all the fluilds in my JD tractor. I haven't crawled under the truck yet to check out the difficulty. The manual suggests synthetic if the rear axle is not limited slip
and regular if it is, yet a maintenance menu from the dealer suggests synthetic. Who is right, also for anyone who has done this service how difficult is it and are there any suggestions or tips. I did read somewhere to make sure you loosen the filler hole bolt first before draining, which makes good sense. Any help would be very much appreciated.