Procedure is the same on both, but the fill plug on the transmission is most likely difficult to get to.
Both plugs are probably 14MM Allen type. There is a special tool that will allow you to get into tight spots.
Remove the FILL PLUG FIRST! The reason for this is so that you do not drain the fluid, then have no way to get it back in. Then with a drain pan underneath, pull the drain plug. After it has drained, replace the drain plug, fill through the fill hole to specification, which for me in both cases is until it overflows, and then replace the fill plug.
Getting the liquids in may take some special equipment. You can probably get a plastic pump of some sort from Pep Boys or some such place. The pump will be more difficult to use on the more viscous rear axle lube.
If you have room, get a pump that goes on a five gallon bucket of 80W hypoid gear lube. This is a great setup for the rear axle, but the transmission will take something else because you most likely be using motor oil or whatever from a quart, or gallon container. The plastic pump that I have fits the threads of a one gallon oil bottle.
Don't forget the old clothes that you can get stained, this can be a very messy job.
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