I completed the fluid change on the front/rear diff and transfer case as well as spark plug change with my buddy (well, I held the tools
) yesterday. Total time was around 3 hours and I'd say 1.5 of that was for the fluid change. Jacked the rear up by the diff (not the cover!), threw stands under the rear, then jacked the front up by the jacking point and threw stands under the front. To get easy access to the front diff, remove the belly pan (around ten or so 8mm screws and a couple 10mm) and the support brace (four 18mm bolts). From there, it's pretty easy access to the fill plug. The Schwaben tool with a couple mm's shaved off of each end worked wonders for all plugs, especially the transfer case. The tool got up in the cramped space around the transfer case with minimal fuss. I have the Schwaben (rebranded Foxwell) tool and I'm not sure if I reset the transfer case correctly as I didn't have a calibration function available, but I "activated" a reset, so I guess it worked. Threw some codes, but I've cleared those and they didn't come back. No issues and I don't know if it's a placebo effect, but everything seems smooth now.
Now I just have to decide if I want to have the transmission fluid changed. Half the people say "don't touch the ZF" while the others (myself included) like to change ANY drivetrain fluid at regular intervals. It's been a no-brainer for all the manual transmission cars I've owned.