can't help you on the manual trans, but for the diffs it's easy.
park the truck on a level surface..very important.
1) get yourself something like this :

. It's a manual fluid pump. You'll need it for the front diff (and possibly the rear). and also get yourself some thread sealant. I use the paste one :
http://www.canadiantire.ca/AST/browse/8 ... ?locale=en
2) get a 1/2" ratchet. It will fit directly in the fill plug on the diff. Always unscrew the fill plug first, cause if you drain and can't unscrew the fill plug....well... you're screwed !
3) drain the oil by removing the drain plug, again using the ratchet.
4) for the diffs , I use 75W-90. So put back the drain plug (don't forget the sealant) . DO NOT Overthight .. There is no pressure to hold anything, I would say tight the same thing as your engine oil plug. Then start filling. When the oil start coming out from the fill hole, you're done. Put back the plug (again with the sealant).
Do the same for the other diff.
For the Transfer case, the oil is different depending on your TC case. If you have the auto mode (dial inside the cab), then you have the atx14a. This transfer case uses automatic transmission oil !! This is very important. Same procedure as the diffs. If you go underneath, you will find the fill and drain plug on it. Just make sure to use the good oil, or you'll kill it.
S.