Thanks Pachieh!
Sounds like I could definitely do the diffs and transfer case. I am pretty mechanical and try and do all my own maintenence. Did the rear differential fluid and manual tranny fluid on my 2015 corvette but you don't have to do any calibrations on that vehicle.
Is this the Foxwell you mentioned for do the calibration of the transfer case after you change the fluid? Not calibration needed after doing the diffs?
https://www.amazon.com/FOXWELL-Autom.../dp/B019QCG5RE
Vehicle only has 43K on it guess I need to look up and see when it is time to change the fluid on the diffs and transfer case. Never done coolant or brake fluid either.